The story of the Brown Elf was one of the most intriguing vignettes in the Dragon Kings supplement. Sadly, no rules were offered for these types of psionically endowed creatures - or as I call them “ultra-phrenics”. Here is a 3.5e template to create your own ultra-phrenic humanoids.
Interesting, looks similar to a human mutation (or subrace) Villichi.
I do feel all such talents must somehow be balanced and be options people can learn (some slowly some with a huge headstart). Like talent for sorcery could be something passed through a bloodline or obtained from a mystical situation (born during astrological event, exposed to strong magic, or some destiny). But I prefer this can also be obtained by one’s actions, be that obsessive study or training, experimenting with rituals or even a pact like warlock.
Many games have a system of advantages and disadvantages that could help add balanced extra options. Typical disadvantages are restrictions following a code (vow or belief), aging, injuries and insanity/derangements. These could have a penalty like a -1 to a score and allow to spend a point on some benefit. Benefits can be a level of wealth or influence (increasing exponentially), specific items or allies. You could also have enemies or owe favors to allies like a negative wealth.
Unspent points can be represented as a karma / fatepoint / edge / luck rating. You can win and lose some based on what a DM throws at you, and earn extra by good roleplaying. Any of these may change suddenly with magical healing (with costs luck/… or give another disadvantage).
Extra psionic talent is a great benefit. Instead of a Wilder class, a psion (or any class) could buy a combination of drawbacks and benefits, giving less control for more power. This can give extra circumstantial bonuses when enraged or desperate, and of course give good role-playing opportunities.
More permanent abilities are better suited as class abilities, extra could be added together with a penalty like specialized powers. Later one can remove these penalties instead of picking a new ability.
This can be combined to achieve the above talent. A psion may have a telekinetic specialization and be extra talented but have a derangement (anger). If found sooner the boy above could have learned proper technigues and contain his rage. This is separate from class and either remaining a specialist or become an all-around psion.
This template isn’t balanced for PCs. I didn’t include Level Adjustment for that reason. The template also a glass cannon until the NPC gets some levels under its belt.
I figure that Rajaat was an ultra-phrenic.