V Sge is a peculiar, highly luminous long-period (12.3h) cataclysmic variable that displays a supersoft emitting component (SSS) when in the faint phase of its V~10-13 range of variability. It appears to be undergoing heavy accretion from its more massive secondary, almost certainly at, or above, an Eddington-limited rate, indicating that it is in a very rare, short-lived phase of its binary evolution, placing it firmly in the SSS-DD channel for eventually detonating as a SNIa. Its complex and highly variable set of optical emission features, from Balmer and HeII up to high ionisation emission lines, including strong fluorescence features, have made it a target of detailed spectroscopic studies going back 60 years. It is the brightest galactic SSS, yet we only have poor constraints on the donor properties. We have obtained VLT X-Shooter spectra of V Sge as a function of orbital phase, revealing multiple components in both high and low ionisation lines which have allowed us to track V Sge's principal emitting regions. These results will be placed in the wider picture of our understanding of mass-transfer processes in the SSS. These results will be compared with very recent results on the only BeX SSS with a He donor in the LMC, and other short-lived SSS transients in the Magellanic Clouds, indicating that the long-sought Be-WD systems can be found. This has implications for the properties of the Be equatorial disc, which are a feature of many HMXBs.