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Part 2 of The What Lies Beneath Series
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Published:
2026-07-24
Updated:
2026-07-24
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1/?
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Dynamight's Guidebook to Expecting Fatherhood (He Has No Idea What He's Doing)

Summary:

Bakugou Katsuki spent eight years secretly planning to marry Midoriya Izuku.
He just forgot one tiny detail.
...He was supposed to date him first.

Or: A collection of fluffy post-canon snippets featuring emergency weddings, impending fatherhood, and Katsuki discovering that being a husband is somehow scarier than fighting villains.

Notes:

Hi!

Thank you so much for reading What Lies Beneath! I had so much fun writing it, and seeing all of your wonderful comments made the experience even more special. I've never had a fic receive this many hits on AO3 before, so thank you from the bottom of my heart!

That said, I absolutely could not sleep last night because this idea refused to leave my head, so I gave in and wrote it.

This is a sequel to What Lies Beneath. In contrast to all the heart-clenching angst of the original, this one is just a collection of short snippets following Katsuki and Izuku after the proposal. Expect lots of fluff, comedy, domestic chaos, and one very overwhelmed expecting father who has absolutely no idea what he's doing.

This will be an ongoing series, so I hope you'll stick around for the ride!

Thank you so much for reading! 🧡💚

Chapter 1: Apparently You Need to Plan a Wedding

Chapter Text

Rule #1: Apparently You Need to Plan a Wedding

 

The night after their tearful conversation:

 

Katsuki: "Let's get married tomorrow."

Izuku: "...Tomorrow?"

Katsuki: "Yeah."

Izuku: "Kacchan, people usually need time to plan a wedding..."

Katsuki: "Already planned it."

Izuku: "..."

Katsuki: "..."

Izuku: "What?"

Katsuki: "I've had a folder."

Izuku: "..."

Katsuki: "...Since eight years ago."

Izuku: "You... have a folder?"

Katsuki: "A spreadsheet too."

Izuku: "..."

Katsuki: "..."

Izuku: "...You made a spreadsheet?"

Katsuki: "I'm an adult."

 

(Then Izuku opens it.)

 

Wedding Budget.xlsx

✓ Venue options

✓ Catering

✓ Floral estimates

✓ Photographer

✓ Rings

✓ Emergency weather plan

✓ Guest list

✓ Seating arrangement

 

Izuku: "Kacchan..."

Katsuki: "What?"

Izuku: "You've been planning our wedding before we even dated..."

Katsuki: "...Maybe."

 

 

Rule #2: Let Kacchan Do Everything

 

Them talking about the wedding budget:

 

Izuku: "I can pay for half."

Katsuki: "No."

Izuku: "Then at least let me—"

Katsuki: "No."

Izuku: "Kacchan—"

Katsuki: "I've literally been saving for this."

Izuku: "..."

Katsuki: "...Don't ruin this for me."

 

Note: After becoming a pro hero, Katsuki only had two major expenses: Deku's hero suit and the "Marry Izuku One Day" fund. Once the hero suit was fully paid for, every spare yen went straight into the marriage fund. Needless to say, it had become quite... substantial.

 

 

Rule #3: The Wedding Invitation Was a Phone Call

 

All Might getting a call from Katsuki at 2:00 AM that day.

 

All Might: "Young Bakugou?"

Katsuki: "We're getting married."

All Might: "..."

Katsuki: "..."

All Might: "...Congratulations!"

Katsuki: "You free next Saturday?"

All Might: "...NEXT SATURDAY?!"

 

Note: He wanted to get married the following day but Izuku stopped him. Izuku reminded him that wedding venues don't usually accept twenty-four hours' notice, so after several hours of negotiations, they settled for one week later.

 

 

Rule #4: Just... Let Him Marry Izuku (He’s Desperate)

 

At the tailor shop the following morning:

 

Tailor: "When are you planning to have the wedding?"

Katsuki: "Next Saturday."

Tailor: "...Next... Saturday?"

Izuku: "K-Kacchan wanted tomorrow."

 

The tailor just slowly turns to Katsuki.

 

Tailor: "...Tomorrow?"

 

Katsuki looks offended.

 

Katsuki: "What? We compromised."

 

 

Rule #5: Kacchan is Very Efficient

 

Tailor: "Most couples spend six months to a year planning."

Katsuki: "Sounds inefficient."

Izuku: "Kacchan..."

Katsuki: "I've been saving for years. I already know the venue, and the guest list. I already picked the rings...”

 

Izuku slowly turns toward him.

 

Izuku: "...You WHAT?"

Katsuki: *blinks* "...What?"

Izuku: "You already picked the rings?!"

Katsuki: "I had to know what size to reserve."

Izuku: "..."

Katsuki: "..."

Izuku: "...How did you know my ring size?"

Katsuki: "You sleep like the dead."

Izuku: "WHAT DOES THAT HAVE TO DO WITH ANYTHING?!"

 

 

Rule #6: Todoroki Shouto Knows Everything

 

Shouto arrived at the tailor’s, sat next to Katsuki:

Tailor: "Um... why is Hero Shouto here?"

Katsuki: "He invited himself."

Shouto: "Correct."

 

Izuku, standing on the fitting platform while the tailor adjusted his suit, gave a cheerful wave.

 

Izuku: "Hi, Todoroki-kun! How did you know we're getting married?"

Shouto: "It’s my DynaDeku senses."

Katsuki: "..."

 

 

Rule #7: Kacchan Does Not Cry

 

Izuku is literally just trying on the first suit.

The wedding is a week away.

Katsuki is already fighting for his life.

 

Izuku: "Kacchan?"

Katsuki: "...Shut up."

Izuku: "Are you crying?"

Katsuki: "I'm not."

Izuku: "..."

Katsuki: "...It's dust."

Izuku: "There isn't any dust."

Katsuki: "...Tailor dust."

Tailor: "...Sir, you've been crying since the tie."

 

Mitsuki walked in, took one look at Katsuki's face.

 

Mitsuki: "He's crying already?"

 

The tailor nods.

 

Tailor: "He's cried four times."

Mitsuki: "..."

Tailor: "We've only measured the inseam."

 

 

Rule #8: Let Shouto Handle It (He Knows)

 

Wedding Planner: "What color palette were you thinking?"

 

Katsuki opens his mouth.

 

Shouto: "Emerald green, burnt orange, ivory, and gold."

 

Everyone turns toward him.

 

Wedding Planner: "...How did you know?"

Shouto: "Father likes warm colors,” *points to Izuku.* "Mother likes green."

Katsuki: "..."

Izuku: "..."

Katsuki: "...Who the fuck are you calling Father?"

 

 

Rule #8.5: Let Shouto Handle It (He Really Knows)

 

Later at the florist’s:

 

Florist: "Any flower preferences?"

 

Katsuki scratches his head.

 

Katsuki: "I dunno. Whatever he likes."

Shouto: "Midoriya likes baby's breath, white camellias, and sunflowers."

Izuku: *blinks* "...I do?"

Shouto: "You smiled the longest at those."

Izuku: "..."

Katsuki: "..."

Shouto: "It was in my notebook."

 

 

Rule #8.5.5: Let Shouto Handle It (He Really Really Knows)

 

Then the tailor…

 

Tailor: "Would Mr. Deku prefer silver or gold cufflinks?"

Katsuki: "..."

Izuku: "..."

Shouto: "Silver. His freckles stand out more against cooler tones."

Tailor: "..."

Izuku: "..."

Katsuki: "...How do you know that?"

Shouto: "I have eyes."

 

 

Rule #9: Kacchan Announces the Wedding

 

They invited Class A for an emergency reunion. The drinks had barely arrived before Katsuki stood up.

 

Katsuki: "I've got something to say."

 

The table immediately quieted.

 

Katsuki: "...We're getting married."

 

Silence.

 

Then—

 

Mina: *shrieked* "WHAT?!"

Denki: *slammed both hands on the table* "I KNEW IT!" 

Ochako: *just crying*

Eijirou: *launched himself at Katsuki* "BROOOOO!"

Tenya: *was somehow standing before anyone noticed* "C-CONGRATULATIONS!"

Tsuyu: *smiling* "I'm happy for you two."

 

 

Rule #10: The Wedding’s Urgent (Apparently)

 

Izuku laughed nervously.

 

Izuku: "W-We were actually hoping everyone would come next week..."

Momo: *blinks* "...Next week?"

Kyouka: "What do you mean next week?"

Izuku: *playing with his fingers* "Our wedding... next Saturday..."

Class A: "..."

Servers: "..."

Everyone: "...NEXT SATURDAY?!"

 

 

Rule #11: Kacchan is not Marrying Some Extra

 

Mina: "WAIT."

Katsuki: “What?”

Mina: "...You've been saving for a wedding... with Midoriya... before you were even dating?!"

Katsuki: "..."

Mina: "Wait. You didn’t even date at all!”

Katsuki: *shrugs* "I wasn't stupid enough to think I'd marry someone else."

 

Complete silence.

 

Eijirou: *slowly covers his face* "Dude..."

 

 

Rule #12: Kacchan Has Thorough Plans

 

Everyone discovers that Katsuki has been planning this marriage for years.

  • already had a marriage savings account
  • already researched venues
  • already compared photographers
  • already had a list of caterers
  • already knew All Might would officiate
  • already knew Izuku would cry, so he packed handkerchiefs

 

Izuku: *just standing there* "...We've been engaged for... eighteen hours."

 

Shouto delivers the finishing blow.

 

Shouto: "I thought everyone knew."

 

Everyone turns toward him.

 

Class A: "You knew?!"

Shouto: "Bakugou has had a folder labeled 'When Izuku Finally Agrees to Marry Me' for several years."

Class A: "..."

Izuku: "..."

Katsuki: *points at Shouto* "I trusted you."

Shouto: *blinks* "I thought we were sharing happy news."

 

 

Rule #13: Shouto Is the Absolute Supporter

 

Eventually Mina can't take it anymore.

 

Mina: "HOW DO YOU KNOW ALL THIS?!"

Shouto: *looks confused* "What do you mean?"

Mina: "You know their favorite flowers! Favorite colors! Their schedules! Their favorite restaurants! You even knew Bakugou had a marriage fund!"

Everyone: "..."

Mina: "...WHY?"

Shouto: *blinks once* "They're my parents."

 

Silence.

 

Shouto: "So naturally..." *he nods matter-of-factly* "I'm their firstborn."

 

 

Rule #14: Kacchan... Just Accept It

 

Katsuki slowly sets down his glass.

 

Shouto: "..."

Katsuki: "Oi. Shitty Half-and-Half."

Shouto: "Yes?"

Katsuki: "We are literally the same age."

Shouto: "I know."

Katsuki: "So how are you our son?"

Shouto: "I don't know."

Katsuki: "..."

Shouto: "It simply happened."

 

Some U.A. faculty members arrived at the izakaya:

 

Aizawa: "Just let him have this."

All Might: "Young Todoroki has been calling them his parents for years now."

 

Silence.

 

Katsuki: "...YEARS?!"

 

 

Rule #15: Kacchan Forgot To Announce One Tiny Detail

 

Right after everyone finishes screaming about the wedding.

Everyone is still trying to process the fact it's next week.

Then Katsuki clears his throat again.

 

Katsuki: "Oi."

Everyone: "..."

Katsuki: "...There's another thing."

Mina: "WHAT NOW?!"

Katsuki: "...We're having a kid."

 

 

Rule #15.5: It is Just a Tiny Detail

Silence.

Complete.

Utter.

Silence.

Then—

 

Denki: "...WHAT?!"

Mina: *slowly turned toward Izuku* "...Midoriya."

Izuku: *smiles sheepishly* "...Hi."

Ochako: "...You're pregnant?"

Izuku: *nods* "...Mm."

 

The entire table EXPLODES.

 

 

Rule #16: Shouto Knows About It... Again

 

Eijirou has stopped functioning.

Denki is lying face-down on the table.

Tenya has somehow broken his glasses.

Mina is crying.

Tsuyu is crying.

Ochako is crying harder.

Momo is already calculating baby shower ideas.

Meanwhile…

 

Shouto: *calmly raises his glass* "Congratulations."

 

Everyone slowly turns.

 

Mina: "...YOU KNEW TOO?!"

Shouto: "Yes."

Mina: "FOR HOW LONG?!"

Shouto: *thinks* "...About sixteen hours."

 

 

Rule #17: Kacchan, Please Tell All Might

 

All Might suddenly realizes.

All Might: "...Young Bakugou... is this why you're getting married next week?"

Katsuki: *looks confused* "...Yeah?"

All Might: "...You really buried the lead."

 

 

Rule #18: Everyone is Still Freaked Out

 

Denki slowly looks at Eijirou.

Denki: "Bro..."

Eijirou: "...Bakugou speedran adulthood."

 

Everyone is still freaking out.

 

Mina: "WHY DIDN'T YOU LEAD WITH THE BABY?!"

Katsuki: *blinks* "...Because we're getting married."

Everyone: "..."

Katsuki: "...The baby was implied."

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