Processes and systems for quenching an effluent. In certain embodiments, the process can include contacting a pyrolysis effluent and a first quench medium to produce a first quenched effluent. A bottoms stream that can include tar and an overhead stream that can include ethylene and propylene can be obtained from the first quenched effluent. The first quench medium can include a first portion of the bottoms stream that can include a first portion of the tar. In certain embodiments, the process can also include hydroprocessing a second portion of the bottoms stream that can include a second portion of the tar to produce a hydroprocessed product. A hydroprocessed bottoms stream can be obtained from the hydroprocessed product. In certain embodiments, the process can also include contacting at least a portion of the hydroprocessed bottoms stream and the first portion of the bottoms stream to produce the first quench medium.