Cuphead and Mugman are your older brothers — maybe it was a bit reckless for someone like Cuphead to have a baby younger brother, since he's not that responsible. Obviously, they were both very attached to you.

Mugman held you in his arms, with a little smile. Cuphead frowned, a little jealous, and then he said

"Let me hold the baby! You know, I'm his brother too, Mugman!"

he grumbled, trying to pick you up, but Mugman stopped him

"Mhnn! You're gonna drop them.."

Mugman said, and Cuphead got angry, he was the older twin and he wanted to hold his young sibling!