Arlan is an electro destruction character that uses a sword in battle. He is perhaps a prototype for what a continuous hp-draining destruction character looks like in Star Rail. In Genshin, Xiao was the original destruction character with continuous hp drain for years until Fontaine came.

His E drains his hp to do more damage. His E does not cost sp (but does not generate any). So he has a choice of using his ba or e (drain hp). His Q has 110 energy cost and does a blast nuke.

Abilities that grant buffs for hp over 50% tend to have better synergy with Bennett and Furina (and in HSR's case Luocha).

For example when Wrio's hp is above 50% it enhances his AA. So in this sense he has synergy with Bennett. However, Wrio needs to be below 60% hp to use his buffed CA, so in this sense he has anti-synergy with healers and Bennett. Otherwise, Wrio synergizes well with Furina.

Noctis is hp scaling so forget Bennett synergy. However, Noctis gains dmg bonus the more hp he has, so he synergizes with healers in general. Otherwise, his 3 stack passive causes antisynergy with double hydro and Furina.

Lyney CA deals more damage when he drains his hp, which requires being above 60% hp. Thus he synergizes well with healers and Bennett.

As for Xiao (Alatus), he is an example of an hp-neutral character. He will drain his hp regardless of threshold and synergizes with Bennett and Furina's buffs regardless of what hp he is at. So in this sense, Xiao is perhaps one of the more flexible hp-fluctuating dps.

Lunae does not have any hp fluctuation so why is he destruction? Perhaps it is because he can give different enhancements to his ba, so like Arlan (or the destruction trailblazer) he can choose how much damage to deal (flexibility). In this sense, Alhaitham can also be considered a destruction character as he can choose how many mirrors to frontload his damage. But then the question becomes: why isn't Qingque a destruction character (as she can also enhance her dmg)? This is where the lines between erudition and destruction become blurry.

It seems hp fluctuation is a subset of destruction (signature, characteristic of the path), but destruction also includes other things (that can overlap with erudition).