It's nice to see "Arrow" return to a serialized plot line so tied to the fate of Star City. Last season, so much of Oliver Queen's mission was related to fixing problems caused by his small social circle of frenemies, which was kind of hard to get behind.

This season, "Arrow" has doubled down on its commitment to Star City, once again broadening the scope of this story and allowing thematic resonance on a larger, systemic level. This show may never be one especially interested in fleshing out its setting, but "Arrow" cares about Star City again — and that makes for some pretty great superhero TV.

"Arrow" also doubled down on its commitment to the brotherhood between Oliver and Diggle in tonight's episode. "Brotherhood" may have been all about Team Arrow's quest to save Andy Diggle from the clutches of Damien Darhk, but — on a thematic level — it was also about further cementing a friendship that started season 4 oh-so-damaged. And you better believe it was heartwarming. An actual line from Diggle to Oliver in tonight's episode: "My brother needed me. The green one." Be still, my bromance-loving heart.

But the fun didn't stop there... Here were the seven biggest moments from "Brotherhood."

Diggle's bro is a ghost.

Not literally. That may be what Diggle thought for the last eight years since Andy Diggle's presumed assassination, but turns out Little Diggle isn't so dead after all. He pops up as one of Damien Darhk's notorious ghosts. Because no one is ever dead on "Arrow." Enough so that Felicity can actually deliver this piece of advice to also-not-dead Ray Palmer with a straight face: "When you come back from the dead, you're supposed to start living again." (Though quote of the night may go to Laurel, who tells Diggle: "Resurrected siblings are kind of in my wheelhouse.")

Diggle isn't so excited about Andy's still-alivedness.

For a dude that spent so long trying to avenge his brother's death, Diggle is not very excited about the news that Andy is, in fact, alive. Still reeling from the reveal that H.I.V.E. took down Andy because his criminal operations were too much competition for their own criminal operations, Diggle doesn't seem to think it's worth risking Team Arrow's lives to save Andy.

I have to say: This rang false for me. Diggle might be shocked by his brother's return, but one folder from a questionable source does not a total crisis of faith in one's brother make — at least not to the extent that Diggle wouldn't even try to save his own little brother.

Whatever my feelings on the weirdness of Diggle's reaction, there was one thing I was completely certain about: David Ramsey brought it in tonight's episode. He had me tearing up multiple times in this episode and wishing that "Arrow" gave him more to do on an episodic basis.

Bromance saves the day.

Though Diggle might not think it is worth risking the lives of the members of Team Arrow to save Andy, the rest of Team Arrow does. Which is kind of sweet, and kind of condescending.

TBH, Diggle's motivation felt like another example of "Arrow" contorting Diggle's character so that someone else can be given believable character motivation and development — usually Oliver. Here, Diggle's insistence that he doesn't think his brother is worth saving is the perfect platform for Oliver to push off of. Oliver has to believe that someone who abandoned his family and did horrible things can be worth saving because he himself fits that profile and Oliver wants to believe that he himself is worth saving. For me, this conversation between Diggle and Oliver was one of the highlights of the entire episode, even if I'm still not buying Diggle's anti-brother stance.

Team Arrow nabs Andy.

Whatever the emotional motivation, it makes tactical sense that Team Arrow would want to capture and interrogate one of Darhk's men. Andy Diggle is as good a choice as any, so that's exactly what they do. With the help of Ray, who manages to figure out where the ghosts are stationed based off of that cyanide tooth retrieved in an earlier episode, the gang storms the compound and nabs Andy. Now, he lives in a cage within the lair with a perpetual brood-face on. When Diggle asks him if everything Darhk says about him is true, Andy just says yes, but something tells me there is more to this story than what "Arrow" is so freely giving us.

James Bamford's direction was totally refreshing.

Tonight's episode was helmed by first-time director James "Bam Bam" Bamford, who usually acts as the stunt coordinator of "Arrow." The result was a refreshing aesthetic style that particularly shone in the action sequences. The filming style for those fights was similar to the way in which Bamford usually films his pre-visuals for all of the stunts — i.e. handheld long shots that clearly displayed the choreography of the fights.

It's that last point that might have delighted fans the most. One of the criticisms of season 3's action sequences was that, because of the way they were shot, we weren't able to clearly see the elaborately-choreographed fight sequences. That's not the case here. Filmed in the midst of the fight, it felt like we were on the ground with Team Arrow and it was scary, thrilling, and oh-so-refreshing — almost like a first-person video game, at times. More, please.

Oliver rebuffs Darhk's offer of an alliance.

It seems that Darhk really truly doesn't know that Oliver is The Green Arrow. We know this because, in tonight's episode, Darhk approaches Oliver about "working together" as mayor and shadowy crime lord. (He doesn't say it that explicitly, but the intent is clear.) First order of business: Oliver needs to drop his platform of cleaning up Star City Bay.

Oliver seriously considers it. Darhk is starting to get suspicious of Lance, and Oliver thinks that he might make a better man on the inside. He talks to Felicity about it, which — after an entire season of Oliver not consulting anyone about anything — still manages to both surprise and delight me. Her opinion? His stupid plan to take down H.I.V.E. from the inside is exactly like his stupid plan to take down The League from the inside, and remember how well that turned out? Besides, Oliver decided to run for mayor so that he could give the people of Star City some hope, and they deserve that. Oliver deserves that.

Diggle agrees with Felicity. (Because, of course, the BFFs discuss it and, of course, Oliver isn't even surprised when he realizes that they have.) Together, they convince Oliver to fight Darhk "in the light." #OTA

Thea has some kind of resistance to Darhk's magic.

In an unexpected turn of events, Thea and Darhk run into each other in the hallway of the ghost compound and Darhk's magic doesn't seem to work on her. In fact, rather than hurt her in any way, it draws the bloodlust out of her without her having to kill anyone. Which is, you know, nice. Especially because she has started beating up random douchebags in bars, which, while entertaining, is probably not a good habit to get into.

Luckily, Malcolm Merlyn just happens to be back in town (to check in on Thea). Though Thea has ignored her biological father for most of the episode, she turns to him when she realizes what Darhk's magic has done, demanding he help her find a way to use Darhk's magic to curb her bloodlust for good. Anything to keep Merlyn around, amirite?

Though we learned a bit more about Darhk's organization in tonight's episode, this storyline is moving a bit slowly for me. We're still not sure why Darhk cares about the world's "disease" so much. On the whole, he doesn't seem to like the world that much. This was fine in the first few episodes of the season, but we're well into season 4 at this point. I wouldn't say no to understanding a little bit more about Darhk's character.