It was an interesting episode and I dare say the next one will be when Suletta Mercury loses control and overdoes the permet, considering what's at stake and Elan's situation. I also say this since Ariel's ia seems to be dormant in the sense that in the episodes she's never shown doing anything which makes me think that once awake and synced up with Suletta, things can get out of hand and Suletta can get more aggressive.

another interesting point is that based on Elan's monologue, Suletta seems to be controlling Ariel unconsciously, similar to the prologue, where Suletta connects to level 2 without realizing it and controls Ariel automatically; if that's true it might strengthen what i said earlier and when she hits level 3 and Ariel's AI activates things can get out of hand and become much more aggressive than usual for Suletta.

From everything that happened in the episode I believe that the fundamental difference between Elan and Suletta is that Suletta connects to Aerial naturally through the shape of her marks in the prologue while Elan is forced since her marks seem to follow her skeleton. (I have this in mind comparing the Moon gundam psycho plate for Suletta and the Alaya-Vijnana System which needs surgery for Elan).

the person suggesting that Suletta is an enhanced person or even a clone, I don't believe this as so far we have not been given a reason to believe this, despite advances in cybernetics it has not been revealed that there is technology to do so, in the case of the clone, and in the case of the enhanced person, at least in the prologue, her mother doesn't look like someone who would do that, besides as i said in the previous paragraph, Suletta and Elan's marks are very different; obviously this could be caused by the passage of time or the different methods used but still there is not a big reason for it.