Freminet is Lyney's sibling and the creator of Pers.
I. M. Pei is known for designing the Louvre in Paris, seeing how an NPC named Peixiu was also introduced in 3.8 before Fontaine.
His diver helmet resembles the big daddy from the bioshock game. So then where are the little sisters?
Freminet's passion is diving, a possible reference to how Sieur Freminet invented the first scuba diving gear.
Freminet is a physical dps whose burst allows E spam (like C6 Xiao or Cyno). Generally in games like Genshin, abilities that allow infinite spam are considered the creme of broken. This is why C6 Xiao and C6 Itto are highly valuable. Everything else is usually considered good or great. But to break through to god tier realm, one usually needs to incorporate some aspect of infinity.
But infinity may not be enough. High scaling is also needed. If Freminet could spam nukes with his E like C6 Xiao or C6 Itto's CA, then he would be one of the most broken dps.
As the old adage goes, infinity times zero is sometimes zero. A simple example is the limit: $$\lim_{x\to \infty} f(x)g(x) = 0$$ where \(f(x) = x, g(x) = 1/x^2\). The point is, yes infinite things can be good, but you want to have infinite nukes for godly damage rather than infinite times zero.
Speaking of which, some French figures such as René Descartes, Cauchy, Legendre, Laplace, Fourier made several contributions to mathematics and physics. The European colonial era also saw the rise of several brilliant minds such as Isaac Newton, Albert Einstein, etc. This is alongside the technological advances and industrial revolutions of the Fontaine nations.
His E starts Pers timer, which lasts 10s. During Pers timer, his NA will deal both cryo and physical dmg (frost waves). Using NA will increase the level of Pers timer, up to 4. He can use his E again anytime during this state (think Dehya's second E). Using his E again will deal dmg based on the level of Pers timer (shattering pressure / SP). The higher the level, the more physical damage it deals. Lv0-3 shattering pressure does mix of cryo and physical. Lv4 deals just physical (and apparently yeets Pers), with fairly high scaling. Also when he reaches lv4 Pers timer, his next NA (or E) will automatically deal shattering pressure and end Pers timer (using N5 or E will have same effect). E has 10s cd (can enter Pers timer every 10s).
His Q does a cryo nuke and decreases his E cd (like Cyno Q) by 70%, so it becomes 3s. Also each NA will increase Pers timer level by 2 (making it easier to spam lv4 SP mini-nukes). Also like Cyno Q, it changes the energy particle generation of his E. And like Cyno, Freminet is quite energy efficient and can get his burst back on cd as he can spam E during his Q.
He can be played 2 main ways: 1) as physical driver and 2) as cryo E spam dps.
When using his E, he can do N5 (N4 + lv4 SP). With Q, he can do E, N3 (N2 + lv4 SP), and then repeat.
Overall, Freminet's kit is very unique and quite fun. If they made a 5* version to deal more damage, it could potentially be quite good. For example, the Q could also give 100% physical dmg bonus. It may also drain hp, or perhaps Freminet's NA/E drain hp, so that he becomes a destruction character that can synergize more with Focalors. If he triggers a certain number of reactions (like frozen, shatter, superconduct, etc.) it will give a multiplier to his NA or E damage.
The test run had him on 4p blizzard with Mika in a freeze team (no electro for superconduct). This works more with E spam.
4p Pale Flame or Bloodstain could also work. Then there is the meme TF build or along similar lines the sac greatsword build. If doing E spam, one can consider 4p Golden Troupe for 45% E dmg bonus (a meme but actually an option).
For weapons, Skyward, Wolf, Redhorn, Fish, Snowtombed, Sac, Favonius can work.
His miscellany video also showed some other teams, such as pairing him with hydro for shatter freeze. He can work with Mona, Beidou, Yelan, XQ, Yae, Kuki, Fischl, Furina. He can even be played in hyperbloom teams such as with Nahida, XQ, Kuki, truly one of the teams of all time.
Mika can work to buff physical. Chongyun can work for cryo build.
Freminet broke through the 1st island chain or the 1st line of defense of Albedo and Morax. For three years, Xinyan was the 4 star with the highest base atk. And Albedo and Morax were slightly above her. But now Freminet became the first 4 star character to have higher base atk than Albedo and Morax.
See island chain for more info.