concept where Jonathan knows Clark is gay in a lowkey begrudging i'll sorta accept it but never talk about it way, and obviously thinks Clark knows, but he doesn't. So when he's trying to explain why Lex Luthor could be so dangerous and bad and why he should stay away from him, he gingerly explains that this older, kind of suave kid from Metropolis might try to "take advantage of your...proclivities, son" to uncover his secret. Of course Clark freaks out and is like wHaT pRoClIvItIeS dAd.
But then every time Lex looks at him too fondly for a beat too long, he's thinking about it. Every time Lex says something or acts like he's in love with Clark or attracted to men, Clark's like omg what if Dad's right and he's trying to seduce my secret out of me. Which makes all of Lex's girlfriends look even more suspicious since in Clark's mind, they're the real thing and his affection for Clark could be feigned.
And then when Clark finds the room this adds even more fuel to the fire of 'he never even cared about me as a friend,' because just as much as you wouldn't investigate your best friend behind their back, you wouldn't try to sleep with them as part of a scheme either. So Clark HAS been aware of all of Lex's flirting and has been wanting to believe it like he's been wanting to believe Lex is really a good person but thinks he's been proven wrong on both counts.
(Lex is very much in love with him, but has been trying to hide it to be all noble with the underage kid or whatever and to not to lose his friendship. And neither Jonathan or Clark yet realize bisexual people are a thing.)
