What is a trial court's duty to instruct a jury on every theory that is supported by substantial evidence?

"A trial court must instruct the jury on every theory that is supported by substantial evidence, that is, evidence that would allow a reasonable jury to make a determination in accordance with the theory presented under the proper standard of proof. [Citation.] We review the trial court's decision de novo." (People v. Cole (2004) 33 Cal.4th 1158, 1206.) The trial court's duty to instruct sua sponte on a defense " ' "only [arises] if it appears that the defendant is relying on such a defense, or if there is substantial evidence supportive of such a defense and the defense is not inconsistent with the defendant's theory of the case." ' " (People v. Maury (2003) 30 Cal.4th 342, 424.)