10 Doctor Who Companions Who Should've Met A Different Doctor
2. Turlough And The Ninth Doctor
Tulough's origins were kept shrouded in mystery until the very end. Until that point, all fans knew is that he was manipulative and cunning and working entirely to his own agenda.
If he was pitched against the Ninth Doctor the way he was against the Fifth, both would be hiding their respective pasts and ordeals from the other whilst attempting to outmanoeuvre them. The power play between the two could constitute the story arc of the series, building up to the finale in which both would finally spring their traps as both would have employed a keep your friends close but your enemies closer tactic to disrupt the other's plan. Gripping.
Aside from this, if this was to take place pre-Rose (continuity admittedlly taking a bit of a beating), the Ninth Doctor would be considerably more vicious and turbulent, creating a parallel to Turlough's realistic and pessimistic natures. The two would make a dark TARDIS crew but an interesting one nonetheless.