Paul's contribution to the show was definitely for eye candy and for the action scenes. Younger and more physical than the other two 'leaders' of SHADO, he was perfect for it. And the girls liked him, especially the teenage girls who weren't old enough to find his cockiness annoying. The reason fanfic writers have trouble seeing him as anything but an ambitious and arrogant prig is the poorly executed episodes that make him appear that way. 'Psychobombs' is an episode in point, where even after repeated watchings, you really have no clear idea why he brought Linda to HQ. You can read whatever you like into the episode, but looking at what is actually onscreen there isn't a clue. Which is a problem with poor writing and directing, not a problem with the character.
I tend to base my opinion of him on Straker's own assessment, seen over the course of the season. He saw potential in him and was obviously grooming him for eventual command. So, in spite of poorly written and directed scripts, that's how I see him as well.
When I wrote the 'Conover Saga' I had not seen all the episodes for years, and had only recently gotten the videos. So I saw Paul more as I remembered him from the final episodes, where he was more Straker's right hand man, and I portrayed him in that more mature manner.
However, later sagas and stories I wrote suffered by my exposure to the DVDs, when I watched the episodes back to back often enough to really be annoyed by his character. As with Ginny Lake, it was more the fault of the writers than the actual portrayal of the character. The actors did the best with what they had, and considering that they were given only one take per scene, I think they did an exemplary job.
I pick on Paul a lot, simply because he's such an idiot most of the time (especially in the early episodes where he flies off the handle so easily.) But he can be a very strong character when written well (as seen in some of the later episodes), and I hope enough fanfic writers have realized that so that his image in the fanfic world isn't completely downgraded to buffoon.
My personal favorite story about him is one of my own from the Conover Saga: 'Chain of Command.' (But that may also be because I thoroughly enjoyed doing a remake of 'The Maltese Falcon.') However, it still remains in my mind as one of his shining moments in fanfic history, and I'm proud to have been able to give him that. My second favorite is Yuchtar's 'Overexposed,' where we see a much more mature and intriguing Foster (as well as getting to enjoy a threesome with him and Straker and Gina!) See? He's excellent eye candy.