Ah ... That's really easy , and you don't even need behaviors
Only 1 little event ...
Every Ticks : *NameofTheObjectthatfollowsthemouse* | Set Position
X = Lerp ( *NameofTheObjectthatfollowsthemouse*.X , Mouse.X , 0.5*dt )
Y = Lerp ( *NameofTheObjectthatfollowsthemouse*.Y , Mouse.Y , 0.5*dt )
Cheers