In the Wii U/3DS version of the game, she can upgrade Rodea to make him more powerful.
Ion is a cheerful and energetic young woman. She loves tinkering with machines and creating new ones, even though the other inhabitants of Garuda fear machines. She tends to blindly trust her "gut instinct". She believes all machines have hearts like humans do.
Ion is a very good mechanic, and managed to fix Rodea, though she has a tendency to make mistakes when she's rushed.
Machines she created include:
- the Ion Wave, an airship
- the Ionceiver, a transceiver installed on Rodea that lets him communicate with Ion (or whoever is inside the Ion Wave)
- Mr. Detecto, a radar she uses to monitor things
- Detecto Jr., another radar installed on Rodea who lets him detect things
- Mr. Kablammo, a bomb used to blow up a Naga base in the desert
Ion lives in a hidden village with her grandfather, who raised him alone since the death of his wife, Ion's grandmother. She's been tinkering with machines since she was a child, creating one when she was only 5.
Ion finds Rodea buried head first in the desert. She extracts him from the sand and repairs him, though he has lost most of his memories. When the Naga Empire threatens Garuda again and Rodea flies off to defeat their machine soldiers, she follows him with the Ion Wave.
*****SPOILERS FOR THE REST OF THE GAME*****
Later, they meet Tonio who needs medical herbs. When Rodea refuses to help, Ion helps him remember that he has a heart. After that, Ion accompanies Rodea throughout Garuda, leading him to each of the Chronos Towers and giving him indications.
She doesn't follow Rodea inside the Chronos Towers; instead she waits in Garuda. Before Rodea leaves for the second Chronos Tower, she makes him promise to come back safe. They will make the same promise for the remaining Towers.
After Rodea comes back, they stop by Ion's home village, where her grandfather scolds her for her recklessness. As he lectures her, Ion gets abducted by Rylus, who wants to exchange her for Rodea's half of the Key of Time. Rodea sets off to rescue her, followed by the other villagers aboard the Ion Wave. Meanwhile, Rylus asks Ion if she know about the snow cave, but she doesn't.
Rodea finds Ion and Rylus, and refusing to give away the Key of Time, he fights Rylus above the Ion Wave, in the middle of the sky. When Rylus is defeated, he decides to jump down, taking Ion with him. Rodea grabs her just in time, and Rylus eventually decides to let her go, falling alone. Ion reunites with everyone, and after the Fire Chronos Tower is stopped, she continues the journey with Rodea.
Rodea finds the snow cave that Rylus mentioned, and starts recovering his memories. Ion worries that Rodea will forget about her if he retrieves all of his past memories.
After they stop all of the Chronos Towers, Valghis shows up and opens the R-Gate. When Rodea crosses the R-Gate to the past, Ion follows him. Before Rodea enters Geardo's throne room, Ion makes him promise that they'll go back to Garuda together. Rodea defeats Geardo and Valghis, but Ion is put in danger when Geardo, under a new form, mistakes her for his daughter, with whom he wants to be reunited. Rodea saves Ion by defeating Geardo again.
Ion and Rodea are about to go back to Garuda and the future together, but Rodea explains that he cannot keep his promise, as he has to stay behind to close the R-Gate. Despite Ion's protests, Rodea opens the R-Gate which sucks the Ion Wave, sending Ion alone back to the future.
Ion wakes up in a new future. She finds and repairs Rodea again, who still remembers her after 1000 years.
- If you watch closely in the fully rendered cutscene that takes place right after Rodea escapes the first Chronos Tower, you can see Ion give Rodea a quick kiss on the cheek.
- Ion displays many sociopathic behaviours throughout Rodea the Sky Soldier, such as a lack of shame, poor judgement, insincerity, need for stimulation by living on the edge, and inability to learn from experience, all of which are demonstrated by the two times she builds bombs and has Rodea set them up, nearly killing him twice in the same way. She also manipulates Rodea into allowing her to accompany him by constantly reminding him that she's the one who fixed his arm. (Sources: http://www.mcafee.cc/Bin/sb.html https://www.psychologytoday.com/articles/201305/how-spot-sociopath )
- It is heavily implied by the game that Ion is somehow related to Princess Cecilia, be it as a descendant or reincarnation. (spoilers for the game from here) In the Wii version, Cecilia is all but confirmed to have died in her fall at the beginning of Chapter 21, which takes place right after she teleported Rodea to Garuda with half of the Key of Time, so unless she had already given birth (which is unlikely as she is only 18), it would be impossible for Ion to be her descendant, and is likely a reincarnation. In the Wii U version, after the ending, a scrolling wall of text like at the beginning of the game appears, and states that Cecilia was saved by Rodea, and implies that Rodea believes Ion to be her descendant.