On the Siblings–Friends axis (兄僕線), Tian Kui sharing the Siblings palace means the directly opposite Friends (僕役宮) carries the relational mirror of whatever the configuration produces. Tian Kui is one of the six classical auxiliary stars (輔星) that condition every chart configuration; it’s Yang Fire in element, paired classically with Tian Yue (天鉞), and activates strongly in daytime charts (chart-holders born during daylight hours). The Siblings palace classically governs siblings / peers / business partners.
Classical phrasing for Tian Kui in this register: 天魁天鉞夾命, 貴人扶持 — ‘Tian Kui and Tian Yue flanking the Self palace: noble persons sustain the chart-holder’. The general practitioner reading: configurations needing a break, transitions where outside support shifts trajectory, career inflection points. Specifically in the Siblings palace, the auxiliary-star register of noble-person luck interacts with the palace’s siblings / peers / business partners domain — supporting it (when the chart structure aligns) or testing it (when it doesn’t).
Textbook reading: siblings or close peers tend to play this register, with the chart-holder benefiting from peer-level help. Tian Kui as an auxiliary star tends to lift this configuration when the chart structure is sound; when killing stars share or oppose the palace, the lift can be partial. The reading shifts noticeably when the chart-holder enters a 10-year luck phase that re-activates the Siblings palace.
For the synthesis itself. The full practitioner-grade reading layers: (1) which Main Stars share the palace and which sit in the opposing Friends (僕役宮); (2) which other auxiliary or killing stars share the palace (especially the partner star, Tian Yue (天鉞)); (3) whether any of the Four Transformations (四化) activate the Main Stars in this palace for the chart-holder’s day stem; (4) day-vs-night chart distinction; (5) the active 10-year and annual luck cycles re-shaping the palace. This is the synthesis the Zi Wei Dou Shu Masterclass teaches in depth. To check whether this configuration applies to your specific chart, plot it free at the ZWDS calculator.