I know that some Timelords feel that their Loom names are too pompous, to elitist. I have no Timelord name, as I hadn't been granted a TTC yet. I was still in my first regeneration when I fled Gallifrey in Sen, just having finished all my academic work at the Academic and awaiting graduation. Most people don't realize that all Gallifreyan's get a “normal” name upon birth. For the Patrexe Chapter, the super-long Timelord name added on the end is actually the name of their Titan, the organic being under the mechanics of a TARDIS. It is granted to a Junior Timelord upon Academy graduation when they receive their TTC. Sen was never given a proper name for me to take, as he was never officially commissioned.
Back on topic… often Timelords will take a title to better illustrate their personality. The Madman chose well. Before I go into the events surrounding how he pretty much drove all of US mad, I should give you some background on him.
Madman is one of only a couple Timelords to not enter SL-Space per The Abbot's good graces. He basically broke in. He was shot in, really.
Madman's origins are somewhat fuzzy. It's presumed that he fought in the Time War and somehow escaped the Last Day, but not without loosing his memory of everything before. His first awareness was of being in a dying TTC with virtually no power, and Gallifrey was gone. In the shake up surrounding the last days of the War, the barriers between universes started to break down. Madman took advantage of this to create a somewhat unique power source.
His power source was actually the inspiration for Sen to create what would eventually become our own Eye of Harmony. Madman has a compressed pocket universe inside his TTC. Super-compressed in both time and space - it's virtually a restrained Big Bang. The energy flowing from it is intense, even by Timelord standards. But it's not the energy that is the issue. It's the fact that this universe is active. With life… entire civilizations actually. Billions of sentient lives. And they're all tied into the telepathic circuits of Madman's TTC – right into his head. He calls them the Narwhals. A Timelord going slowly more and more insane from the constant din of a universe's worth of minds.
This is a problem for him, but not really anyone else. Until someone decided to take control of those civilizations and invade the pocket universe. That someone was called Tethseram.