Possess her body.

Jason approached his mother's spirit and tried to touch or move her, she was pretty much rock solid for a spirit, he couldn't move or get a response out of her.

He panicked, what if her body started to die without a soul?, Anxiety swelled up inside him and he tried to touch her physical body to see if he could reconnect them, he saw that by placing parts of himself in her he could see her body twitch slightly.

He remembered that in lots of media, ghosts and other manner of incorporeal being can take hold of people's bodies and do stuff with them. He wasn't sure about trying to control his mother or anything but he didn't want her to perish for some stupid experiment her son's soul did. It was time for desperate measures.

He tried to insert himself in her but it wasn't working. He moved through the air like a jellyfish underwater, trying to enter her body in different spots, her body just reacted with slight, almost unnoticeable twitching. He came to reason, this was too rough and then...

“A right, meditation and astral projection. Calmness, no rushing. It leads nowhere good”

Jason took the same meditation pose as her mother and placed himself slightly above her body but still below her floating spirit nearby, he then did the opposite of trying to project, he imagined himself going back to a body, in this case, he pictured the body of his mother.

Jason suddenly felt very weird, if his out of body experience was weird, it was about to get weirder, he started to see himself from several third person perspectives, he could see and feel how from his soul emerged this similar string like the one that he had already seen, it slowly connected itself to the bellybutton of his and mom. It felt warm. Welcoming even. A sensation of security.

The aura came back, this time it was the same white color as his and started to surround the body of his mom, the eyes of the body opened, they showed the green hue of his mom's spirit, it started to fade.

Very slowly, he sunk into his mother, he felt many things, but none really seemed to make much sense, rebirthing sensation?, A stupid question but made his mind tolerate the sudden transition easier.

His spirit kept descending in his mother's figure, and eventually, it fully sunk into her, her body went slightly limp for a few moments, then several spasms started to run through her body which kept fighting to maintain the same posture though all of this, eventually the eyes of her body rolled back, followed by a very long sight and a violent deep breath attempt, filling the lungs of the body to its limits while her back arched. The aura then disappeared and the body regained his meditation position, eyes still rolled back

Jason then felt a sudden shock, feelings invaded him, the world went dark.

The eyes of his mom's body slowly rolled back to their place, a small tear fell from each one.

Jason then saw light and then the room, and then he was back... Not quite if we are being real

He had done it, he had possessed his mom's body