You have a strong addiction which is a detriment to your life, taking up space in your mind and causing you to do things you wouldn't normally do and ignoring reason in favor of feeding this addiction.
Choose a drug or activity (such as sex or gambling) to be addicted to; you are obsessed with or psychologically dependent on satiating this addiction and will go to great lengths to do so. This activity must be engaged in regularly depending on severity (see below), and for every day you haven't engaged in this activity you suffer Resolve and Sanity damage.
Like a negative status effect, this is measured in Intensity with each one building upon each other and its effects stacking with lower intensities. You start at Low Intensity upon taking this trait.
Addiction
Low Intensity: You feel a slight craving for the object of your addiction and seek to satisfy it every now and again. You can go up to a week without suffering the negative effects of your addiction, after which you begin suffering 2d6 Resolve and Sanity damage.
Moderate Intensity: Every now and then the pang to engage in your addiction really eats away at you. You can go up to 3 days without suffering the negative effects of your addiction, after which you begin suffering 3d6 Resolve and Sanity damage.
Severe Intensity: You regularly find yourself chomping at the bit just to get your next fill of your addiction. You cannot go a single day without at least satiating your addiction once, after which you begin suffering 3d8 Resolve and Sanity damage.
After 1 week of suffering Resolve and Sanity damage, you either have a chance of breaking your addiction or progressing to the next intensity. If you are reduced to 0 Resolve or Sanity while abstaining from your addiction, your addiction progresses to the next stage rather than causing you to acquire a mental disorder. If you manage to go the entire week without being reduced to 0 Resolve or Sanity instead, your addiction lowers to the previous step (or being completely recovered if it recovers from Low Intensity).
If you manage to break your addiction you acquire 1 TP if it only progressed to Low Intensity, 3 TP if it ever reached Moderate Intensity, and 6 TP if it ever reached Severe Intensity. If you instead relapse and your addiction progresses to the next stage, you receive 2 TP each time this happens until you reach Severe Intensity.