Tyler and Hayley's relationship is complicated as they started as good friends, but their friendship later turned bad when Hayley betrayed Tyler by setting up his pack to be massacred. Tyler also later threatened her and her baby's lives for his vendetta against Klaus Mikaelson.
Hayley stays with Tyler, when Dean is ordered to try to handle Connor, Hayley and Tyler try to talk him out of it. After Klaus threatens Tyler, Hayley is upset he's just gonna back down. After Dean is killed, Hayley cries over his death and Tyler is there for her. She's upset that they couldn't help him.
Hayley and Tyler, along with some of Klaus' hybrids drink in Dean's honor.
Tyler and Hayley are no longer friends because she let Klaus kill all the hybrids as a sacrifice. She also broke Caroline's neck in order to prevent her from interference in Shane's plan to have Klaus massacre his hybrids.
Hayley briefly returns to Mystic Falls and told Klaus that she'll never have a shot with Tyler.
In Bloodletting, after finding out about the baby, Tyler kidnaps her. Taking Hayley out to the Bayou. She's tied up in the cabin clearly worry for the baby and herself since Tyler is a wild card. Tyler uses the baby's blood to turn a werewolf into a hybrid who then becomes sired to Hayley. He kills the newly turned and Hayley escapes leaving Klaus to deal with him. This was the last time Tyler and Hayley ever interacted.
Hayley: (To Tyler) "So this is where you've been hiding huh?"
Hayley: "You mean who I killed? (Tyler nods.) Boating accident. We were drunk, I thought I wasn’t." (She sips her champagne and looks away.)
Tyler: "So, what’s with you chatting up all these old timers, huh? My mom. That professor guy."
Hayley: "That professor guy is like, thirty, and he’s hot and smart." (Hayley laughs. Tyler sees Caroline and Klaus walking across the lawn together. Klaus has offered his arm to Caroline and she seems to have gladly accepted it.)
Hayley: "They're gonna get us both killed and we're just sitting here."
Tyler: "Kim's right. The point of breaking the sire bond is being free. They don't have to listen to me."
Hayley: "Yes, they do. Ty. You can make them. Hybrids are werewolves first. Wolves run in packs, and every pack needs an alpha or they'll end up challenging each other if we're dominants. Kim is challenging your position as alpha. You need to put her in her place, now."
Hayley: "Hey, you attacked me, remember? You ambushed me, in my own backyard."
Tyler: "It's not your backyard, it's Klaus'! You're shacked up in that mansion with that psycho. A long way from the girl I've met in the Appalachians, helping other werewolves."
Hayley: "Tyler, I'm sorry, but a lot has happened since the last time I saw you."
Tyler: "You mean that you're pregnant? A hybrid baby, yeah, I know all about it. I've been roaming around the Bayou, asking questions. Let me tell you what I learned. This crescent birthmark means you come from a big-shot family. Some kind of royalty for the werewolves of this region. And right here, this is all that's left of them."
Tyler is now a werewolf and Hayley is now a hybrid.
Tyler initially embraced his hybridization as it allowed him to avoid transforming unless desired as he hated the curse while Hayley initially rejected her hybridization because it made her act similar to a vampire and she had embraced the "nobility" of the curse shown to her by the Crescent Wolf Pack.
Tyler is the first TVD main character to find out that Hayley was pregnant with Klaus' child.
When Hayley was cursed to be trapped in wolf form, Tyler triggered his werewolf curse, at the next full moon.