》I have never seen any Swapverse!Killer so I will come up with something.

Marvul and Krait (Swap!Killer) met after a battle with Xcellence and Halluciv. Krait healed him, gave him food and a place to stay meanwhile.

Krait works at a coffee shop that is located next to his house, so he had an easy access to check on Marvul.

After staying a couple of weeks, Marvul started to get attached to Krait and he didn't want to leave the AU.