Doctor Who/Fringe crossover

‘a blue box suddenly appears in the lab, a goofy young man pops out from it, flinging open the doors, grinning madly. Walter smiles back in a curious manner, rather than Olivia whom draws out her gun and points it at the man. This shocks and scares the man’s two young companions, a girl with firy hair and man with a pointy face. Peter on the other hand just sat back staring, because somehow, somewhere his seen this man before. That’s when the man spoke

“Peter Bishop, what pleasure to see you again, it seem like I need you and your father’s help, fancy a trip in the TARDIS?” the mad man with the blue box said in his cheerful, carefree manner’