respectful, honest
愿 centers on an inner attitude of sincerity and careful regard: being respectful and honest in one's conduct.
愿 combines 原 (origin, source) with 心 (heart), suggesting a heart that returns to its original, sincere state—hence respectful and honest. The exact historical development is uncertain, but the component relationship is plausible.
Inside the original source (原) of a person lies a heart (心) that is naturally respectful and honest. Picture uncovering your true heart at the source of a spring, and it shows only sincerity.
For ゲン, imagine a respectful person named Gen bowing deeply, their honest heart (心) showing through their original (原) nature: Gen -> ゲン.