The Vanguard

That is a relatively plausible theory, “plausible” meaning “possible in another story or another fictional universe”. While it is an intriguing and realistic speculation, it doesn’t serve the poetic beauty of ASOIAF. “Two evil power-hungry men who are plotting to make themselves richer” doesn’t sound very ASOIAF-y to me.

The Blackfyre theory about fAegon. Not because it is incorrect, but because it is too obvious. I like to think that there is more than that. Like Illyrio being the grandson of Aerion Brightflame, and Serra being a Blackfyre.

My theory is built on the assumption that Illyrio is fAegon's father, and Serra is definitely a Targaryen descendant. It may or may not be the case, though it very probably is. The Brightfyre theory holds that Illyrio is actually a Blackfyre descendant in the female line, and Serra is a descendant of Aerion Brightflame. My theory is the opposite; that Illyrio is a descendant of Aerion Brightflame, and Serra is a Blackfyre. 1) Illyrio as Maegor's son Although Illyrio's age or birth date isn't given anywhere, it can be assumed that he is around 45 (which would make his birth date around 255 AC). Aerion's son, Maegor was born in 232 AC, the same year his father died. At the age of 23, Maegor could've fathered a child indeed. This leaves some questions unanswered, like "Why did Varys and Illyrio grow up in poverty?" etc. But this question is also unanswered in the classical Brightfyre theory and the ubiquitous Blackfyre theory. Well, whomever you would think as Illyrio's parents (Mopatis man + Blackfyre woman | Maegor Targaryen + a random woman) likely grew up in poverty as well. What happened to Maegor after Egg was chosen as the king is unknown, but he was likely exiled to, or voluntarily decided to go to Essos. In Essos (probably Lys or Pentos), Maegor probably lived a sellsword's or a cutthroat's life, and was likely not rich. 2) Serra as a Blackfyre It is like a universal fact that Serra is, in some way, related to the Targaryens. No speculation is needed here. 3) Why would Illyrio, a trueborn Targaryen, help the Blackfyres? This is a relatively plausible argument, but also quite answerable, even in the classical Brightfyre (Illyrio Blackfyre + Serra Brightflame) theory. Maegor probably (and expectedly) developed a hatred towards the Targaryens during his time in Essos. He also probably indoctrinated his child Illyrio (or Serra if you support the classical Brightfyre theory) with the same hatred. Thus, this led Illyrio to sympathize with the Blackfyres, and father a child with one of them. Ironically, this would make fAegon's claim quite strong, as he descends from the eldest male line of Targaryens alive. In the classical Brightfyre theory, fAegon is a descendant of Aerion Brightflame through his mother, which would make his claim somewhat weaker. I am curious about your opinions regardless of which theory you support.