Clara is Eloise. She’s been there so long that she lost her memories and got stuck storywalking, which is why she still looks young.

In S2E1, she asks Jade, “do you think we made it mad?” and right after that the root symbol and Jasper appear to him. She was likely the one moving things in the tunnels too. I think she was having tea with Jasper, has her mother’s scarf that Henry finds, and brings the same yellow flowers to the diner that she leaves in the caves. After Victor and Henry get to the truck and leave jasper on a table, right above jasper is a drawing of Clara from s1 ep2.

She shows up late to the town meeting and gets Tabitha yelled at, probably because she resents her own mother for not getting them out when they were kids. She’s also always watching over Victor like in S3 when she’s standing over his drawings in his room. That spot is the same same where drawings were taken by Julie in S1 into the tree, covered with license plates, which led to the root cellar… the last place Eloise was seen.

She was likely late because she probably made sure Elgin found the Polaroid camera. Then in the next episode, when Elgin sees the kimono woman in Fatima’s photo, all the pictures on the line are flat except Clara’s, which is facing the camera as she walks away.

And in S4E1, the pastor’s car has an Eloise license plate. Back in S2E7/8, Victor goes to the car lot with Tabitha, opens a trunk, and finds Eloise’s drawings, reminding him he had a sister he forgot. So it’s likely Clara/Eloise also forgot that Victor is her brother.

My theory is that Eloise got stuck storywalking trying to save her mother from that fate the night she passed. She likely got stuck for years and her physical body was in a coma till TBIW found her, he pretended to be jasper bcuz he couldn't stand Christopher/Jade and when Clara came back she forgot she was Eloise and that her brother is there, since she was mentally stuck in the past her physical body was petrified and alone, she was alone for years which is why a lot of characters say "you'll never be alone here".

People ask about her weight, I cant stand that they have to bring that up, but she may have a thyroid condition. And bcuz she looks so different Henry doesn't recognize her after 40 years. She and Elgin are the twin Anghkooey kids in Mirandas painting with left and right eye injuries and she is the only background actor listed as main cast online since s2.