Introduction
The promise of the Treacherous Allure feat is to magically befriend a creature, then betray them as soon as you’ve gotten what you want from them.
The concept of the feat is fine, but it also depends on the Charmed condition. Resistance and immunity to Charmed are common (though not ubiquitous), and the Charmed condition nearly always ends when the creature takes damage, so the benefits of the feat are often short-lived.
I see some value here for the Arcane Trickster. Using Charm Person to handle social situations can make up for poor Charisma, and Inevitable Betrayal may be helpful to get Sneak Attack in the first turn of combat. I wouldn’t rush to add this feat to a build, but it’s an option.
Ability Score Increase
Any mental stat. Perfect for spellcasters.
Enchanting Presence
Charm Person is fine. It’s useful in some social situations, but remember that your target knows that they were Charmed when the spell ends, and that will likely come with consequences. Charm Person is also widely available on numerous spell lists, so getting it Prepared for free isn’t a huge benefit.
Inevitable Betrayal
If you’re done talking to your Charmed target, Advantage on your first attack against them is nice. It’s not hugely impactful, but it may be reliably useful in a game where a lot of social situations turn violent. Stabbings at a nice dinner, etc.
However, the majority of spellcasters don’t rely on attack rolls beyond low levels, so this is only useful if you’re one of the spellcasters that does. Warlocks, War Clerics, some Bards, Bladesinger Wizards, and other gish builds all work here.
The Charmed condition is available from a number of spells. Hypnotic Pattern is a personal favorite.
