((Its her NOBODY not her Heartless))
Namine.
Yeah, but it got back to Sora because of Kairi. Sora WAS a Heartless when he saved Kairi, but Kairi protected his Shadow Heartless form with her love and pure light and brought him back, the first ever as far as anyone can tell.
In 1, partly. The rest, No
Sora and Kairi's hearts are linked, so when sora became heartless to save kairi, he also created namine' as a special witchcraft nobody True, but Kairi never turned into a Heartless because she had all light in her heart. Her heart couldn't go into darkness, so it went to Sora instead.
Kairi never actually became a Heartless, but you're referring to what happened in Hollow Bastion's castle. Sora's and Kairi's hearts were linked, so Naminé was created when Sora sacrificed his own heart.
No. In Kingdom Hearts only Sora became a "Heartless". However, Kairi initially lost her heart on Destiny Islands. Instead of her heart being consumed by darkness and turned into a Heartless, her heart went into Sora's body because of their shared destiny. When Sora found Kairi's body, he released both his heart and her's. Her heart went into her body while his was Consumed by Darkness and he became a heartless. So They did not simultaneously become heartless because by Sora becoming heartless he gave Kairi's heart back to her. And when Kairi lost her heart, Sora still had his.
Kairi never became a Heartless. Since she's one of the seven princesses of heart, she is pure of heart and devoid of darkness, so she can't succumb to the darkness and become a Heartless. Naminé was actually born from the transfer of Sora's heart into Kairi. Sora's released heart caused Sora to become a Heartless and produce the Nobody Roxas, but the transfer to Kairi also created the Nobody Naminé.
He heart landed in Sora somehow
Well, Kairi doesn't actually have a Heartess...but Namine is her "Nobody". According to the game a "Heartless" is made when a person yields to darkness and the vessel that has been left with no heart becomes a "Nobody". If you can remember at KH1, Sora gave up his heart for Kairi turning him into a heartless. Since Kairi lost her heart and didn't become a Heartless, she only has a Nobody which is Namine.(my theory for Namine's ability to control the memories of Sora's heart was because of Kairi having Sora's heart and vice versa, their hearts are directly linked.
If you mean when Sora was a heartless, than it just disappeared. Sora was a heartless, Kairi gives him a hug, Sora hears Kairi's voice and light returned to his heart. He turns from his heartless form to human form, also still making Roxas while turning back into a human.
When Kairi lost her heart, Sora sacrficed himself then gave it to her. She was alive, but Sora turned into a heartless in the process. Kairi then gave a bit of her heart (which was his) to him.
He was for a few minutes until Kairi turned him back by hugging him.
probably happened in KH1 when destiny island got attacked by heartless