You can speak to him here without fear. It is in Demon's Ruins by the second bell that you should not talk to him. To avoid his default ending you can use poison pyromancy on the bugs in Demon's Ruins or level up enough in Chaos Servant covenant to open door in Demon's Ruins and do it manually. The location is past the lava and orange fog wall on the right. Not sure why you would want to deprive yourself of that ending...Luckily enough the archer on the right just fell to his death before I reached him. A funny resolution for that infamous moment which I was apprehending.
So I reached the bonfire where you find Solaire and explored most of the rooms nearby. The room with the paintings is stunning and I'm surprised to see that the figures depicted look perfectly realistic (except for Gwynevere), as if they are real portraits. I looked up some guide for his quest and read that you shouldn't talk to him if you haven't fulfilled some condition--can't remember the specifics. What do you recommend I do to avoid his bad ending?
A few screenshots I took for the occasion:
Also, that last picture reminds me of this poor bastard in Dark Souls 3...