Colm is rather snide and arrogant, but genuinely cares for Neimi. He is also quite proud of his thieving prowess. It is often hard to tell if Colm is exhibiting his uncaring for others or if he is simply clumsy. In a conversation with Moulder it is revealed he had burned a pack filled with Moulder's belongings twice, Moulder then says he is 'concerned about the condition of Colm's soul.'

Colm has a weakness for Neimi being sad or crying, which she does quite often. He will often try to pretend he doesn't care or pester her about being a "crybaby". If the two obtain an A Support, Colm will be unable to keep up his facade and comfort Neimi.