Title says it all.

For some reason still not known to them, the Assassins and Templars of old have somehow appeared in the modern age. Now it's up to Desmond, Rebecca, Shaun, and William to take care of them until they are able to come up with a way to send them back to their own time. Still, helping his ancestors return to their homes would be much easier if they stopped acting like children.

"Children make you want to start life over." Can a little child bring two enemies closer and even more? The coming of an unexpected blessing made Shizuo and Izaya realize that they need each other and can start over. Mpreg in the first chapters/bit of angst and drama. Shizaya (sorry for the crappy summary!)

If someone had told Desmond that he and two of his ancestors would be spending the day at an aquarium, he was very sure he would have laughed and asked what exactly said person was on.