Board Thread:The Heroes of Olympus/@comment-33183217-20170925150145/@comment-31481772-20170925154724

I think:

1. Gaea's body is destroyed but she isn't truly gone. Some strong-wiled individual could collect the scattered pieces of her consciousness and put them together in a new body, like Luke did for Kronos.

2. Tartarus can send part of his consciousness to Earth. However, that part would be much weaker than his full form. During Ouranos' reign, Tartarus was probably scared to manifest on Earth because of his much stronger brother. After Ouranos' death, he just didn't care much about going to Earth.

3. '''When Kronos killed Ouranos, he could never reform again. By himself.''' But someone could try to artificially re-form him, like Luke did for Kronos.