Alamais(e), Lofwyr's brother is implied to be one of the dragons that mated with the elves and took their betrayal particularly hard.
Almaise took the disobedience of the immortal elves so badly that his new nickname among the dragons became "Elfbane". As I recall from the Earthdawn book on dragons, Almaise sired the lineage of the immortal elves that ruled Wyrm Wood (note the name), which would later become Blood Wood. But these new elves (who were told how much better they were than other Namegivers, so we might have Almaise to thank for elven egotism) got restless and by the end of the Second World decided to rebel, and Almaise's eldest daughter Caynreth wounded him, giving him a scar that he still has. This made him pretty pissed off, and he basically spent the whole downcycle during the Third World stewing in his anger. Almaise tried to come back and resume his rulership during the Fourth World, but the queen of the Elven Court at the time either didn't know or didn't care and told him to piss off, so he killed her. Almaise spent the rest of Fourth World (or at least, the time up until Earthdawn is set... who knows what happened after that) obsessed with getting Wyrm Wood back. That's on top of his existing bitter resentment towards his brother (not really seen in Earthdawn, but known to Shadowrun players as Lofwyr) for kicking him out of their old home turf in prehistoric Germany. (Basically he's all the ruthlessness of Lofwyr, plus a bitter inferiority complex because he came in second. Be afraid.) After Almaise's little misadventure, the dragon Council strictly forbade crossbreeding with the younger races. (And one of them did get kicked out for trying to father his own army to take over the world.)
(It should be noted that Almaise wasn't necessarily the only dragon involved, but the info in the Book of Dragons was written by the Outcast for his servents/children, and Mountainshadow/Dunkelzhan notes that he'd rewritten history to pin the whole thing on Almaise alone and ignore the fault of any other dragons involved. Like with SR sourcebooks and their Shadowtalk, ED sourcebooks didn't always tell the truth.)
Back in the days of Earthdawn, Almaise was considered antisocial and full of himself, even by
dragon standards. He hadn't attended the Council for centuries and was one of the few dragons to openly admit that his goal was to seek power, and was a dragon-supremacist who wanted to rule the younger races (rather than just meddle shamelessly) at a time when such an attitude ran contrary official policy of the Council. As best I can recall, pretty much the only dragons in the region who were more unpleasant were the Outcast and Udun (a.k.a. Sirruag). So you can imagine how nasty he might be in Shadowrun, now that (as the behavior of Sirruag demonstrates) there are apparently no longer any rules restraining them.
Of course, all this only covers how the immortal elves of Wyrm Wood came to be. I seem to recall some implications that there were also immortal elves involved with Thera. If so, I'm not sure what their origins were....
