I should mention, I'm not entirely up on my cannon, so if I get a fact wrong, please let me know. I own nothing!
The moment Ed sees that pretty-boy face, he knows there could be trouble. The cocky attitude Sam displays as he swaggered (really, there is no other word for it) after the Commander cements that impression. Damn kid is a hot-shot, good-looking and knows it, professional with enough attitude to piss pretty much everyone off.
The Timmy's run is sweet, sweet revenge for such a fun first impression – act like a little shit, get treated like a little shit. The fact that his double-double is still hot upon arrival impresses Ed just a little.
Sam's constant professionalism, despite being relatively new to police-work, raises a few eyebrows. Sure, negotiation training is a slow, laborious process with many moments where Ed's tempted to shoot himself instead of his 'hostages', but the kid's trying.
It's one night when they're all out for drinks that Ed starts catching on. Sam and he close down the bar that night because the next day is a day off. They're only a little tipsy (either Sam has a water IV that's keeping him hydrated or he's pouring most of his third pint into the plant behind him without Ed catching on), but when Sam is dissecting the day, he mentions Jules' name with a sort of wistful tone that Ed only remembers Greg having when Joanne had just left him.
Then Jules gets shot. During her recovery period, Ed notices that Sam is very helpful, and grits his teeth. Since Jules is technically not on the team in an operative manner, Ed keeps his mouth shut, but swears that one toe out of line will send him to Greg. Dealing with Donna instead of Jules is just one more uncomfortable situation.
By the time Jules is back, Sam is no longer mentioning Jules, wistfully or otherwise. Ed's sort of glad that he can stop watching so carefully, but still winces when Steve shows up at SIU to take Jules out. C'mon, Jules, he thinks to himself, That's just mean. He's happy that Jules is dating someone, anyone else, but Sam doesn't need his nose rubbed in it, eager puppy as he may sometimes be.
Ed loses track of everything when Toth arrives because while the longevity of Sam and Jules surprises him, it's Greg he's more worried about. He sincerely hopes that the two kids have learned a lesson, but now he's trying to keep Greg on track as he can, a sense of normalcy. Oh yeah, and his baby is colicky and Sophie's not happy with him and everything that's happening at work, as it takes him away, and it's just one more card in this fragile house so the worry about Jules and Sam, the open-and-shut case, gets put away.
It stays gone until Jules is in a room filled with anthrax and Sam is frantically waiting at the door that only Ed's sense of right dictates that Sam really shouldn't rush in and save Jules first. By this point, he is just so tired of this that when Sam saves the civilian, Ed glares into a camera that he's sure Toth is monitoring. This is my team, right or wrong, and I'll be damned if you take that from me. There's so much unhappiness right now that Ed just wants to have some hope that it will work out and things can be fine.
When Toth is finally finished with them, so to speak, Ed just feels relieved that he can stop worrying about the Sam-and-Jules dilemma as being out of his hands and focus on everything else. And he thinks, maybe, as Ed observes the two arriving separately to the picnic, they could work out in the end.