Integrating Model, Serializer and Algorithm in a tree structure coherently

Question

I have a tree-like structure of objects, linked to each-other with foreign keys.

Each object's fields are stored in a model. Each object has a serializer. Each object has a few routines, now stored in an algorithm class.

There is a serializer that recreates the tree structure into a nested dictionary.

How do I merge these 3 facets of each object into a single object?

Should I create a child object, which inherits from the three others (scary)? or should I include the model and the serializer inside my algo class as inner objects (seems more modular and independent)?