[quote=@Lonewolf685]
I know that the character's they parallel are anathema to each other, but an alliance between Seyrun and Wes would be kind of entertaining...in the "I want to rip your throat out, but this alliance is too convenient" sort of way. They could compete with Berserker and her Master for the most disfunctional odd couple. 
[/quote]

If he can present a reason decent enough for said partnership, Seyrun might consider it, mainly because having Caster on her side would be advantageous. But it would have to be a damnnnnn good reason to overcome the inborn hatred that she has for low-life magi. At least she's not stupid like Kayneth-sensei to think low (or better to subestimate them) of a being as powerful as a Servant.

Furthermore, Berserker will find herself on Seyrun's hands sooner or later. By the going of her relationship with her Master, things will get bloody soon, unless Command Spells are involved.