The series follows "The Gang '', a group of five depraved underachievers: twins Dennis Reynolds (Glenn Howerton) and Deandra "Sweet Dee '' Reynolds (Kaitlin Olson), their friends Charlie Kelly (Charlie Day) and Ronald "Mac '' McDonald (Rob McElhenney), and (from season 2 onward) Frank Reynolds (Danny DeVito), Dennis ' and Dee 's legal father. The Gang runs the dilapidated Paddy 's Pub, an Irish bar in South Philadelphia.
who is related in it's always sunny
Dennis Reynolds Deandra "Sweet Dee '' Reynolds Frank Reynolds (Danny DeVito), Dennis ' and Dee 's legal father