Oh, the left overs of the grammar cases... What a mess of a language. (as if it weren't also the case with Spanish /s)Either could be right depending what comes next, if the people are subjects or objects in the sentence.
"Troll and I went to the shops" -> if you take out "Troll and" then it's right, so needs to be "I".
"They busted Troll and me" -> if you take out "Troll and" then it's right, so needs to be "me".