404(b) applied to witnesses other than defendant
Prior bad act character evidence is generally not admissible (person did something bad in their past so it is likely they did something bad now = propensity evidence).
However, under 404(b) there are exceptions to this rule: evidence of prior acts to show motive, identity, plan, etc.
But 404(b) can be used for witnesses other than the defendant:
Hammer v. State, 296 S.W.3d 555, 565–66 (Tex. Crim. App. 2009)
*Texas and SC have very similar rules of evidence*