As in RE5, Wesker seems to be once again, working for somebody else or himself. It's not clear.
This may be pure coincidence, but at the time when Devil May Cry was a Bio Hazard game, it was a story about Spencer's son named Tony, who went to his father's castle and eventually killed Oswell, after which he took his place as the head of Umbrella.
It really looks like Capcom was inspired by this idea along with the ancient civilization where the Progenitor Virus was discovered. Only Wesker took Tony's place.
And it makes a lot of sense, you know.
For example, Spencer wasn't in Iwao's script, but Wesker already had a forced evolution plan. This plan was written to Spencer later too, so ultimately linking them as father and son figures, where one passes the baton, was pretty clever. Otherwise it would just be a coincidence that both characters have a similar idea.
Needless to say, Wesker was kind of obsessed with Spencer. He was trying to investigate the old man's true intention, and BIO5 explained this by establishing that Albert, as one of the project's children, had a programmed interest in Oswell. It's clever too.
So I think it makes sense that Wesker became the dark inheritor, as The Umbrella Chronicles called him.
If we think about it, every alleged death of Albert is associated with a change in his status quo.
At first, he was the captain of the squad and revealed himself to be a traitor. He was killed by a Tyrant.
He returned as a member of the HCF's owner with his agenda and remained so until 2006, when he changed his mind about Homo sapiens. He allegedly died after falling from a window with Jill.
Having changed his mind about Homo sapiens, he used Jill's antibodies to make the Uroboros Virus less deadly. He lost the battle with Chris and Sheva.
Now Umbrella's leader, who claims to be Wesker, is giving Homo sapiens a chance to become part of his new order.
It's pretty consistent, imo.