Well, perhaps they start to plan for their future together. They could be thinking about things like where they want to live. Maybe they decide to build a house near Camp Half - Blood so they can still be close to their friends and the place that means so much to them. Also, they might start training the new demigods together, passing on their skills and knowledge.
In fanfiction, after Tartarus, Percy and Annabeth could be on a journey of self - discovery together. They've seen the darkest parts of themselves and each other in Tartarus. So they might be exploring who they are now, how they've changed, and how their relationship has evolved as a result. Maybe they take some time away from the chaos of their demigod duties to really understand their feelings for each other.
Their relationship could become more intense. The hickeys might be a sign that they are moving to a more physical and passionate stage. Percy might become more protective of Annabeth as well, seeing how she's so openly showing her affection in this way.
Their relationship is likely to be complex. They are friends and comrades who have fought side by side many times. So, there's a strong bond of loyalty between them.
At first, it might become strained. Annabeth could be hurt and pull away from Percy. She might not want to be around him as much.
Well, in fanfiction, they might be really good friends who are secretly attracted to each other. They could be constantly saving each other's lives and having those little moments of intense eye contact or lingering touches that they don't fully understand yet.
It can develop through this moment of closeness. Just the act of her sleeping on him can show a level of trust, which Percy might recognize and it deepens their bond.
They can develop their relationship by having deep conversations. For example, sharing their fears and dreams about their future together. Maybe Percy tells Annabeth about his insecurities of not being a good enough husband sometimes, and Annabeth reassures him.
The relationship will likely grow stronger. They'll have to rely on each other more for daily tasks and support. For example, if Percy has a bad day at work or school, Annabeth will be there to comfort him right away, and vice versa. However, it could also be a bit strained at times. There might be moments when they feel suffocated by each other's presence, but they'll have to work through those feelings to keep their relationship healthy.
Their relationship might develop through more in - depth conversations. Since they are engaged, they start talking about their future, like where they want to live. Maybe Percy wants to live near the ocean and Annabeth has other ideas, and they have to compromise.
Well, it completely shatters their trust. Percy would be devastated and feel extremely betrayed. He would question all their past interactions and wonder if Annabeth ever really cared about him.