What if Kon secretly collected Red Robin merchandise?
So like it starts with a regular hangout, Connor having to meet him at Gotham because of some reason.
Instead they’re at one of the restaurants and Tim happens to get some Red Robin merch. He goes to throw it away, but Kon goes like “I want it” as a joke, so he ends up taking it home with him. 
Now, usually, he would just leave it somewhere and forget about it, right? No. He tries to leave the figurine at his bedside table and finds it not right. He moves it to his table table, where he does whatever, but it still doesn’t feel good. He ends up having to rearrange his entire shelf to put a space for the Red Robin figurine.
Next time, it’s when he’s flying by a random shop. He flies by his usual superhero merchandise shop he sees everyday, but he immediately sees this limited edition figurine of Red Robin displayed. Since RR isn’t well known, there’s only two days to get this limited edition thing. Kon immediately changes course and goes to Lex.
He leaves Lex Corps with a couple thousand dollars in his pocket. Kon ends up using it all to get the figure. The figure ends up next to the other figurine he got.
This keeps going on and on, until he has nearly a whole shelf full of just his best friend. I bet it would be funny if he had a couple of posters too. Kon could genuinely be doing this subconsciously, like ‘this would be fun to show him later on’, but it keeps piling up because he never has a chance to show Tim.
Eventually, he gets embarrassed about the amount of merch he has of his platonic best friend. When he gets the opportunity to show Tim his room, he does not take it.
And then Tim and Connor start dating. Kon is of course over the moon and excited, but he’s still quite nervous to show his room. In fact, he tries to avoid showing his boyfriend his room because once you enter, it’s just pure Red Robin coded. 
Of course, with him being the detective he is, finds out something is up, and then ends up confronting him. Kon very reluctantly admits that he doesn’t really want to show his room because he has something embarrassing there, and Tim is very reassuring, promising he won’t leave Kon just because of something he has.
Then, Kon is willing to show his room, and once he opens his door, Tim is frozen.
“Is that.. a rare poster of me? From when I was just Robin?”
“..yes. It took me weeks to get my hands on it.”
The weird thing about this reveal is that Tim is, in fact, not weirded out at all. He just takes it in, and smiles at Kon.
Until one day Tim brings him over to the manor for a surprise. He leads Kon to a different room, and Kon is surprised to see himself everywhere.
Tim shyly admits he’s been collecting him too, but he has a lot more because SB is quite popular.