To make things clear, Lee Shen does not have any kind of hostility with Tubians. He respects their way of life and ideologies.
But, the moment Hegerus came looking for Lee, shit just got personal! Lee is constantly searching for his lost love and teammates while he is not even sure whether they are alive or not.
The disappearance of Gauthama cornered Lee Shen to a corner. The Tubian of Serenity proved to be quite useful in turning the tides with his presence alone.
And since Tubians have decided to make contact with Amortals, Lee Shen could use a hand in the battle.
Tubians living their journey the way they want was never Lee's concern until they decided to jeopardise the safety of all living beings of Utopia.
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[The Tubians were here for sure. And...]
"What is it?"
[See for yourselves.]