Recent VHE observations have unveiled a surprising behaviour in two
well-known blazars at opposite sides of the blazar sequence. PKS 2155-304 have
shown for the first time in an HBL a large Compton dominance, high gamma-ray
luminosities and a cubic relation between X-ray and VHE fluxes. 3C 279 is the
first FSRQ detected at VHE. The high luminosity required to overcome the
significant absorption caused by the BLR emission cannot be easily reconciled
with the historical and quasi-simultaneous SED properties. Both cases shed a
new light on the structure and ambient fields of blazars. Contrary to previous
claims, it is also shown that 3C 279 --as any FSRQ-- cannot in general provide
robust constraints on the EBL.Comment: Proceedings of "4th Heidelberg International Symposium on High Energy
Gamma-Ray Astronomy 2008" (Gamma 2008), July 7-11, 2008. Slightly refined
text with updated reference
