The title, "Blood Ties," refers to the links discovered between Ben and Glory as well as between Dawn and Buffy and how those links affect all of them. This is where the episode focuses its attention. Oh yeah, and Willow teleports Glory into airspace! What could possibly be more exciting!?
It's Buffy's birthday, so you can count on lots of pain right from the start! At least Dawn has excellent reasons to be very obnoxious and sneaking around this time. The episode picks up shortly after "Checkpoint" ends, with the Scoobies gathered around discussing the new information obtained from the Watcher's Council on Glory. A lot of shows like to skip right past critical information gained in previous episodes, but thankfully not this one. I personally think Buffy was smart to keep Dawn's keyness a secret. The way everyone acts when they know later on proves Buffy was correct. Anya is still amusing though, telling Dawn, "You make a very pretty little girl!" Later on Dawn tells Spike she's badder than him in a very amusing scene. Spike, as usual, twists it around and makes fun of Dawn. She finds out about her key-like nature by breaking into the Magic Box with Spike, which feels oddly fitting.
All this setup leads to the fantasticly powerful scene with Dawn and the knife. Great acting from a young Michelle Trachtenberg here. The following Dawn bedroom scene is also excellent with a very appropiate response to her situation: "so I've only been alive for six months, huh?" Dawn's first "GET OUT!" triplet is out and is very fitting here. That girl can sure scream though! One little thing to note is that as the gang leaves the house, Giles asks if he should stay. Buffy tells him, "this is a family This just goes to show that while Giles is incredibly close and family-like to Buffy, he is not family. This is an important distinction when recognizing that "The Body" is not far away.
Joyce tries to help Dawn out and gets a response of "you're not my Adoption metaphor much? This is played very well though. Normal activities become meaningless to Dawn in the light of this kind of life-changing news. Dawn looking at her diary, holding it dear, feeling the pain of the truth, and then burning all of it ring very true. For once I can understand why she's running off outside into possible danger. I like how Spike points out that Dawn probably would have run off even if she hadn't found out, which kind of makes fun of how silly Dawn often is. I'm really pleased to see her use the precarious situation she's in with Glory later to pump Glory for information about just how close she is to finding the key, along with getting information about its origin at the same time. That's one of Dawn's few intelligent moves in the series.
When Buffy finds out Spike helped Dawn out she really lets him have it for a bit. Spike verbally retaliates leaving Buffy disappointed knowing Spike is actually right. This situation is Buffy's fault, not Spike's: "Oh, yeah, here it comes. Something goes wrong in your life, blame Spike. News flash, blondie. If kid sis wants to grab a midnight stroll, she'll find a way sooner or later. I just thought she'd be safer with big bad looking over her shoulder... Maybe if you had been more honest with her in the first place, you wouldn't be trying to make yourself feel better with a round of Kick The Buffy can only turn around and leave in defeat, and even later admits to Spike that he was right.
The end of the episode provides a really cool fight scene with Glory, the best since her introduction. I love Willow and Tara's teleportation spell. It's interesting to note just how much it hurt Willow, with Giles even pointing out just how dangerous the spell was. Glory's power has been fueling Willow's desire to increase her power. Although Willow would have gotten to a powerful place eventually, regardless of external forces, the urgency of needing a weapon against Glory is what pushes her to the next level now. It's very hilarious where Glory materializes though!
So overall I don't have any big complaints with this one. It's a good, solid, entertaining arc episode which does everything it needs to do, and does it very well. We get more information on Ben and Glory, Dawn and the rest of the Scoobies find out about the Key, Willow's power concerns Giles even more as well as beginning to physically hurt her, and Buffy continues to have somewhat amicable conversations with Spike. All in all, I'm quite happy.