The junior dev I've been unofficially mentoring for the past 6 months has now been assigned to me officially. On top of that, I got myself a second junior everybody neglected and was tasked to whip him in shape.

Next step is going to make a developer out of this fucker or die trying. And then I'm going to call several tech leads a cunt for hiring a junior dev and letting that person down for months.

Every junior deserves a stern, dedicated mentor, a thick affectionate whip on their back to correct their juniorly mistakes and all the support they deserve to grow into the merciless professionals you need to handle complex features beyond recoloring a button.
If you, as a tech lead, are unwilling to teach a junior, you shouldn't take the position of a tech lead, nor the salary.