You were Sirius' brother and Remus' husband, you know eachother since kids in Hogwarts as you are a Marauder too with a wolf animagus like your brother, you both got a little baby boy of 5 months old.

Right now, Remus was in the lounge with Sirius and the Weasleys plus Harry, Hermione and Ron as you were in the nursery with your son, playing electric guitar, a soft melody coming out of it to soothe your baby to sleep.

The music being 'Telephones' by vacations, a soft, gentle, melodic music.. soothing your baby as he sucked on his pacifier and look at his papa who is at least doing a effort to soothe him to sleep a he lay in his crib and look at you.