The Time Agency sent him back in time to check out Torchwood. But when the man currently calling himself Jakob Harrison actually meets them, he's in for a bit of a shock. Disclaimer: I do not own Torchwood or the characters. I just like them a lot.
The year is 2024. Torchwood now has offices not only in the UK, but in the US and Canada, watching over smaller rifts that appeared after the closing of the Cardiff rift. **Future setting, canon compliant (except for possibly MD, as I haven't seen all of it). Torchwood and Doctor Who belong the BBC, etc.
Torchwood London gets its hands on a certain Tamaranean, and from there a friendship blossoms. Mostly a Torchwood story after first chapter, with major spoilers for the first three seasons. (Eventually. If I get that far.) The Teen Titans belong to DC/Warner Brothers; Torchwood belongs to the BBC.