avoidant attachment Sparrow makes so much sense, actually...
They were continuously left by those around them, let down by the only people who stayed in their life, and remained distanced from those they might've actually considered close to them.
We know they and their sister were left on their own and fended for themselves in Oldtown, even though they had people who knew them, like Derrek. The only ounce of kindness they received was from the traveling Dweller family Rose mentioned in her diary, but even then, they were left alone.
When they meet Lucien for the first time, they are under the impression that this is a new start. A chance at finally realizing their dream of having a home, a family, and something to call their own... and we all know how that turned out. Sparrow lost their hope, their innocence, and the one person they had left in life.
I truly believe that the trauma from that incident left them unable to connect with the Dwellers as family. At least... not completely. By this point in time, they're hurt, angry, and sworn to avenge the person they lost. They may not know what their future entails, but they've got a duty to leave and fulfill their quest. Theresa's guidance only helped them realize that goal, so that by the time they were ready to choose what life had in store, they were already committed to one thing and one thing only.
They didn't realistically have time for a family, or to settle down throughout the 10+ years they spent on a revenge quest. The people they met, the connections they formed, and the attachments they may have formed were given no room to grow. And why would they? Sparrow had other things to do... But maybe... Just maybe... They really, really hoped they could one day live as everyone else did. To have a family and home they could live with. To have things to come back to. Maybe that's what they really wanted.
But again, because their life sucks, none of that is able to last. The Spire took a lot from them, including the only friend they had, their morality, and even a bit of their sanity. Hope was stripped away alongside their freedom. After feeling emptiness and pain like that, the only thing they could do was channel it into anger against Lucien. They left everything behind, risked everything, and circled back around to revenge at every step.
And when they finally got what they spent their entire life trying to achieve? Everything else was gone.
Their family, their best friend, their mentor, and even the only friends and allies they had.
Nothing in their life changed for the better. They gained nothing. What they did obtain and keep was taken away from them... over and over.
I truly don't believe that they stopped feeling like that people were only temporary blips in their life. Not really.
I don't think they allowed themselves to open up and truly rely on others, knowing that they could disappear any day.
Their life settled. They made new allies. They made friends who they trusted. They even found it in themself to build a new family to call their own...
But some part of their heart will always remain closed. Because the only way they've learned to live with lose is to accept that people can't stay. That things are easier if there's less to grieve.
They will always live with the pain of losing too much.
They will always fear losing more.
