The 2018 Lombok earthquake swarm provides a unique opportunity to investigate the fundamental physics that governs the complex rupture on a fluid enriched fault that has strong thermal gradient. The sequence is distributed beneath the northern coast of the Lombok island on the Flores Fault, composing of two Mw6.4 and two Mw6.9 earthquakes and numerous aftershocks. Interestingly, the first Mw6.9 event shows much more asperities, hence more patchy rupture, compared with the second Mw6.9 event. The seismicity captured by 13 seismometers deployed on the island just before the first Mw6.9 event mostly concentrated within a narrow depth range (~5km). The squeezed seismicity and coseismic rupture of the largest events is highly consistent with a volcanic-rooted thermal model, characterized with the elevated depth of the Brittle-Ductile-Transition (BDT) zone.Repeating/similar earthquakes were identified and are mostly located in the rupture area of the first Mw6.9 event, with a large portion overlapping with coseismic slip. This indicates a highly heterogeneous friction and incomplete coseismic rupture on the fault that is probably caused by the stronger thermal gradient compared with the second Mw6.9 event.