Soul Reaver would first have taken Phaerys and Kitharsis to one the bazaars on Dinlete - basically a continent on another world.
You can imagine the place as a vibrant middle-eastern-style market, but filled with travelers from many different worlds and places, including the occasional warp-traveler or other mysterious individual.
For Kitharsis, the visit would simply be so he can seek out any equipment he might like. Soul Reaver keeps a good stash of money around so he would have supplied any coinage, and you can assume there'll be some sort of seller there for basically anything
For Phaerys, the point of visiting the place is to give him a (very) small taste of the many different species and creatures that are out there, even in one small spot of the multiverse, as well as give opportunities for him to speak to others to maybe hear rumours of the rest of his people - this is a spot where you might possibly hear of goings-on elsewhere in the multiverse if you ask the right people.
Soul Reaver won't be forthcoming with explanations on how the Obsidian Slivers work until he's been with Phaerys for a while. Once he has, he'll explain that the slivers are passively tied to his awareness of other peoples' soul energy. When snapped in half, it causes a momentary 'pulse' that allows him to 'see' the bearer's spiritual signature even across the multiverse, allowing him to pinpoint who it was and where they are. As long as he acts immediately, that will allow him to travel to their location. He forges these himself on the Obsidian Island (which Phaerys will likely have been taken to see at some point in their journey), though naturally the materials for their forging would have had to come from elsewhere (so they don't evaporate after leaving the island). The slivers are magical, so possibly Soul Reaver will also need to explain some of the basic concepts of magic from the Mortal Plane.
In the timeskip, Soul Reaver will be going around playing hero - saving people in distress, overthrowing evil warlords/wizards and probably stopping at least one incursion from Inferno by more or less showing up and anticlimatically telling the Daemons to quit it and go home. He'll be primarily using the Eye of Justice to point him in the right direction (with the occasional tipoff from others).
During this time Phaerys and Kitharsis would be traveling through the warp multiple times and get a chance to test out their powers. Phaerys would be free to investigate the whereabouts of his people (the library on the Obsidian Island also contains a wealth of info - most of it historical though). However, Soul Reaver will be pretty driven to 'do his duty' and do the hero thing - since there's always something bad happening that he could stop, he considers it a personal failing if he's not out there stopping it, so there won't be much downtime between the heroics for him.
If any of that stuff sounds like gibberish, check the Board Battles wiki or ask me, I'll be happy to explain.
Does the above fit into everyone else's plans ok?
