"Any card—so long as it exists—has a power that is needed."

nyankotaisho:

As I see it, the part that Ryoken specifically reached out to Yusaku (Ryoken said in #43 that he watched “you” in singular, not plural form in both the original Japanese sub and dub, as in only Yusaku), while hearing all the children’s screaming during 6 months of the Hanoi Project is no doubt an unexpected and important factor that contributes to Ai’s uniqueness as an Ignis, if not the only one.

Interestingly, it never mentioned if Ai had also heard Ryoken’s voice during, but while he watched Yusaku reacted to it, it seemed like Ai also reacted the moment his voice came through, as seen in #19:

And when Ai dissipated, he broke in two:

Another point to note is that as an observer of the Ignises’s growth, it’s also never mentioned if the Professor Kogami ever took notice of Ai’s strange behaviors among the Ignises or not.

Ai also demonstrated to have something akin to human’s sixth sense during Playmaker’s last Speed Duel against Bohman in #72,

It raises the same question that never gets any answer: what exactly was Ai’s “something inside me”.

Highlight the priceless detail “during a duel”. He felt it when Playmaker was dueling. And up until that point whenever Yusaku dueled, he heard Ryoken’s voice.

Playmaker, who also followed and believed in the voice that reached his heart, had no reason to disagree with Ai’s claim right there.

So, the last Master Duel against Bohman wasn’t the only time Vrains had hinted about Ai’s crucial connection to Ryoken. It’s just harder to see than his connection to Yusaku, but it’s there and it counted every single time it had happened. I don’t think I need to mention Ai had acted like a cheeky little shit (and he knew it) when Aqua and the girls questioned him about Revolver in #83, even readily defended Revolver when Soulburner antagonized him.

I did notice something very interesting in season 3 between Ryoken and Ai that may answer this to a certain extent. But then again at this point, every idea is no more than what-ifs and headcanon.