Add all compote ingredients, except the tapioca mixture, into a saucepan on your stove top. Bring to a boil, then reduce heat to medium and cook until reduced by half (about 15 minutes).
Once reduced, add tapioca mixture (if you're using) and cook 5 more minutes until thickened. Allowing the mixture to reduce before adding the tapioca makes it less of a thick jelly like compote and more blackberry centered.
If you prefer more of the jelly part, then you can always add the tapioca mixture earlier. Once thickened, remove from heat and allow to cool.
While the compote is cooking, place all pudding ingredients into a high speed blender and blend until nice and smooth.
Divide pudding into two jars or bowls. Top with equal amounts of compote. Refrigerate until cool and devour!
If you are sensitive to the blackberry seeds you can use a blend and strain method to remove them. Heat everything like above but only until the blackberries fall apart. Then allow to cool and blend.
Force it through a fine mesh strainer to get as much as the juice and fruit through as you can but allowing the seeds to stay behind. Put it back into the pot and continue with the rest of the directions.