Marcus Eriksen is generally portrayed as a the brother that is always pranking Marshall, which can be seen in Arrivederci, Fiero and Oh Honey. All three of the Eriksen children have grown up being rough with each other (The Pre-Nup). They all know how to fight, and rather violently too, as seen in The Fight. Like the other two Eriksen children, Marcus knows how to play Baskiceball, 'the most dangerous and awesome sport in the world' Belly Full of Turkey and at the time was married to Sarah Eriksen. By Something New, he has moved back home. It is unknown if he reconciled with his wife.