Eh, it's what the person drew so I drew it. There is a reason for him to be in it. Darkiplier is a Dark Specter version of Markiplier that the fandom made up based on some creepy vids Mark made. So its been open to interpretation as to what Darkiplier looks like.

I think the person put him in it because they love Markiplier and that it's like a fight scene. They don't have any form of education in art like I do so it's not perfect but I liked it so I drew what they drew.

Though in a way it would look cooler without Mark in it.