Is it load bearing? Weird attic config
Wow, that is one of the most complicated structural “systems” I’ve ever seen. It’s not clear to me exactly which wall you want to remove. 

It does appear that the diagonal supports were installed to rest on several ceiling joists in order to help distribute the roof load. Clearly, the ceiling joists were not originally intended to support the roof...they are too small. In addition, the ceiling supports do not align with the roof supports (joists).

The diagonal supports seem to have been randomly placed and the vertical supports are not installed in any pattern or system either. 

I’d recommend that you hire an architect or a structural engineer, but that could be expensive because they’ll need to spend some time tracking down the roof loads and determining how they are transferred to the footings. 

You could check under the wall that you want to remove and see if there is a footing under the wall (or close to the wall).  If there is, it could indicate the wall is a bearing wall. 

If it is a bearing wall, you can still remove it...you’ll just need to add a header and support posts.