I might make a part 2...

"Shoto!" Midorya called, running down the hallway. It was the couple's first official hero mission and Midorya was very nervous. 

He and Todoroki were inside a large Aerodynamic Metal Transport, or Metal Baby, according to Mei Hatsumi. The walls where sleek and new, and although Izuku didn't need to duck, Todoroki found that he needed to watch his head almost everywhere he went. They were miles underground on a stealth mission.

Todoroki turned his head as Midorya wrapped his arms around Todo's middle, burying his face in Todo's side. Shoto had to lift Midorya off the ground for him to cling to Todoroki, but after that Midorya just hung there like a koala.

"I love you," Midorya said into the crook of Todoroki's neck.

"I love you too," Todoroki was absentmindedly skimming his fingers through Midorya's hair. 

"HEY! EARTH TO LOVEBIRDS," Iida called, rapidly waving his hand in front of the boy's faces. 

"O- oh! Sorry, Iida!" Midorya turned scarlet. Just then, the normal lights went out and were replaced by the red emergency ones. 

A collective gasp went around the transport. Had something gone wrong?

"Brace for impact!" Mei's voice came over the scratchy intercom. 

Midorya instinctively wrapped his arms around Todoroki's neck and the dual-haired boy reached one arm to an overhead grip and another around Midorya's waist, pulling him closer to Todoroki. 

Midorya buried his face into Todoroki's chest as the transport screeches to a halt, sending almost everyone in the train flying as a door is kicked in, reavealing-

(Moving to where Kiri and Bakugo are) (I'm running out of things to write and want to include Kiribaku sry)  

"Brace for impact!" Mei's voice comes over the scratchy intercom. Kirishima and Bakugo where holding hands, and now Kiri pulled Bakugo into him, using his hardening quirk to protect both of them. 

Bakugo hugged Kirishima, for once in his life letting someone protect him. 

Kirishima looked down at Bakugo, smiling his goofy smile in an attempt to lighten the mood. Bakugo scrowled up at him but in a loving way. 

Kirishima turned his back just as they were sprayed with shrapnel and peppered with bullets. He shielded himself and Bakugo as the two sprinted to the main cabin, where Todoroki, Midorya, and Iida surely were. The rest of Bakusquad was already either evacuated or protecting civilians. Denki's emergency electricity was all that powered the train and kept it from collapsing around them (they're still miles underground). Jirou had used her sound quirk to evacuate those who needed to be. 

As they arrived in the main cabin, what they saw was terrifying. Todoroki was using his ice because his fire risked burning the whole transport to the ground, and Midorya had One For All coursing through him at over 100%, fighting off villains. Iida was running messages to the rest of the transport because the communications were down. 

"Go protect Kaminari!" Iida yelled to the couple. Both of them ran to the controls cabin.

They fended off many foes intending to stop the power supply. Denki was going to run out of power, and soon. He was struggling to keep a steady stream of electricity. Kirishima and Bakugo worked together to protect him, though Bakugo had to be careful about his destructive quirk. He only made very small explosions on his fingers, he couldn't even wear his gauntlets. The cabin soon smelled of caramel anyway, though. Kirishima hugged Bakugo after fending off the last of their villains.

"I SENSE PDA," Denki screeched from his place in the corner. The two ignored him

Meanwhile...

Todoroki and Midorya fought well together. Todo made walls of ice and Midorya used them to sneak around and bounce off of, trapping the villains in a maze. Suddenly, a metal barb flashed to Todoroki, nearly going straight through his heart.

Midorya lept in front of it, shielding Todo. The barb went through Midorya's middle, causing him to instantly fall. Todoroki froze all of the villains in a fit of rage, and fell to Midorya's side, trying to stop the bleeding. 

"Izuku! Izuku, stay with me! Don't close your eyes," Todoroki's normally monotone voice hinted at panic. He pressed Midorya's wound as the green-haired boy smiled up at him, his eyes unfocused. 

"I saved you," Midorya stated the obvious.

"Now I'm going to save you. It's gonna be okay," Todoroki said as he used his ice quirk to stop the bleeding and heal Midorya as much as he could. 

"It's gonna be ok," Midorya repeated as he faded out of consciousness, feeling Todorki pick him up bridal style and carry him to the Med Deck. He leaned into Todoroki's chest before losing consciousness completely, though Todoroki kept feeling his pulse.