Westbrook looks like a bit of an akward fit for the Lakers but in my eyes this is a move to take some of the playmaking burden off LeBron. Whatever you think of Westbrook you can't deny the man is an absolute 'horse and is willing to put a team on his back.
The 2018-19 and 2020-21 season's have seen LeBron play the least amount of games of his career as he tries to carry Laker teams and at this stage it is probably for the best if he can dial it back a bit during the regular season.
Davis was obviously meant to be the guy to ease that burden on LeBron but I think we have seen that given his general frailties it is probably best not to overload him either.
For the Lakers having LeBron and Davis fully fit and not run down come playoff time is probably the most important thing. They will have a full regular season to figure out the exact fit with Westbrook to make it work.
As to Westbrook's "personality", from all I have read he is hyper competitive and expects other players to bring the same level of commitment and effort he does every night. As with Jimmy Butler, in some situations/teams this can be seen as devisive or grate on less committed players. I don't really see this as a problem with Westbrook/Butler/etc as a problem with the general team culture. By all accounts Westbrook was the driving force behind a fairly poor Wizards team rallying to get a playoff spot that look highly unlikely midway through the season.