Anderson as a character was, but not his relationship with Shepard, I don't think the extra history was explored in any other media that I know of, just referred to implied.
I personally only have two characters I actually come to hate in the series.
Ashley Williams and Dr. Gavin Archer.
I think Kimberly Brooks is a terrific voice actress, I still can't get over her being replaced in Batman Arkham Knight, she is the Oracle to me.
And I think she did a good job voicing Ashley. But as a character, she was far too angry and aggressive for me personally, she didn't fit in with everyone else on the Normandy for me, since other than Kaidan the rest of the squad were aliens, or as she calls them 'animals'. Plus I didn't like how Captain Anderson just made her stay on the Normandy. I would have liked a choice, and I would have left her on the Citadel. Never have I had a playthrough where I've saved Ashley, and I can't see myself doing so, since Kaidan is one of my personal faves.
Dr. Gavin Archer I hate more.
As someone from England, I find it annoying it whenever English accents are done either as uber posh or London cockney. His voice acting was the least of it though. He was just an awful person for me. What he did to David was more than unethical. I was just so shocked by what he had done, I wanted to go full renegade and just have Shepard shoot him. Meeting him again on Gellix, where he was still wracked with guilt did nothing to make me hate him less.
This.
I keep going back to despising Ashley from her scene on first meeting her in ME2. (assuming she was kept alive)
In that meeting, she throws that diatribe at Shep about Cerebrus, etc., without any discovery as to what's going on.
Especially off-putting, given the whole "we took down Saren together" in ME1, and you should know where my loyalties lie after all that.
Where's the loyalty?
Even though she later apologizes, to me she is all "Ready, Fire, Aim".