These Two Have Appeared In The Same Thingさんのイラストまとめ

Kirito (Sword Art Online) and Ranko Kanzaki (IDOLM@STER: Cinderella Girls) appeared in Tales of the Rays together

Merkava (UNDER NIGHT IN-BIRTH) and Yosuke Hanamura (Persona) appeared in BlazBlue: Cross Tag Battle together

Steve (Minecraft) and a head-crab (Half-Life) appeared in Super Meatboy together.

Larvesta (Pokémon) and Garon (Fire Emblem) appear in Nintendo Badge Arcade together.

Fio Germi (Metal Slug) and Jill Valentine (Resident Evil) appear in SNK vs. Capcom: Cardfighters together

Mametchi (Tamagotchi) and Waluigi (Super Mario) appeared in Mario Kart Arcade GP 2 together

Joker (DC Comics) and Joker (Persona 5) have appeared in Puzzles & Dragons together

Shoto Todoroki (Boku No Hero Academia) and Thor (Marvel Comics) appeared in a Japanese advertising collaboration for Avengers: Infinity War together

Dracula (Castlevania) and Callie (Splatoon) appear in Super Smash Brothers Ultimate together

Grey Fox (Metal Gear) and Pastel (TwinBee) appear in Konami Krazy Racers together