"Like his own soul"
under construction so just throwing everything in here. NSFW art at the bottom.
The time in their relationship where they got too cozy during negotiations while the father/son relationship deteriorated and it freaked Henry II out. Many political elements to this but you can also think of it as "cheating on your Dad with your boyfriend" kinda dynamic the whole time imo. This is probably the most positive the relationship EVER gets in the entire timeline as in them working together and actually loving each other and even then there are still layers of distrust. Richard goes back and forth multiple times between being loyal to Philip and loyal to his father, until one day he makes a choice that ends it all...
"In Exchange for Honor" (Comic) A comic about what it means to share a table.
At this point Philip's sexual rationalizations are mostly "I'm a good and generous person even though I know Richard is definitely a devil's brood and wicked but it's ok, I forgive him, in my grand royal largesse."
In the end they had more drama and kind of drifted after this, over stuff like the rulership of Toulouse and the eternal postponed marriage. After Henry died the relationship started deteriorating rapidly but they were already committed to the group project of Going on Crusade and not killing each other (yet) so a few more years of being somewhat cordial were in order (basically the "going on a road trip to preserve the relarionship" thing)
"Dear to Me" (set in 1189 after Henry's death, pre-crusade + sexual miscommunication bitterness)