祝

Left altar/spirit radical — the side-stacking form of 示, which pictures a stone altar with offerings on top and supports below. Anchors 祝 in the religious/ritual family: 祈 (pray), 福 (blessing), 神 (god), 礼 (ceremony). Marks the wishing as a quasi-sacred act, originally a priest's invocation.

Right 兄 — originally a pictograph of a person with an open mouth (口 over 儿 'legs'), depicting someone speaking ceremonially. In 祝 this is the priest at the altar, mouth open in invocation. The whole character is a compound ideograph: an altar plus a chanting figure, hence 'invoke blessings, pray for, wish well.'