The GTC4Lusso (and the FF, which preceded it) has one of the craziest AWD systems.
Power to the rear wheels is sent from the engine, via a driveshaft, to the rear transaxle just like a typical car.
Power to the front wheels comes directly off the
front of the engine. There is a compact power take-off unit mounted to the front of the engine that's driven directly by the crankshaft. The PTU acts like a two-speed transmission, with one "low gear" approximating the ratio of 2nd and "high gear" approximating 4th. Each output to the wheel has a Haldex-style clutch to control power flow to the wheel. In this configuration, there is no need for a differential.
In operation, the AWD system only functions in 1st through 4th gear and only in certain driver mode settings. When the transmission is in 1st, the PTU is in low (which approximates the ratio of 2nd) and simply allows the output clutches to slip, which makes up for the ratio difference. When the transmission is in 2nd, the PTU remains in low and tightens up the clutch, eliminating the slip. 3rd and 4th operate the same way, except the PTU is in the higher gear.
The piece at the front of the engine with the clear cover showing the innards is the PTU. This is the only mechanical automotive AWD system where power to the front axle doesn't come from the output of the transmission.