how many people have died from tobacco use Smoking: an avoidable health disaster explained 13.6 Smoking and Health –

While he's also made great strides with that, Lopez allegedly still wants him to quit it ASAP

Synaptic Plasticity refers to the strengthening or weakening of synapses (the connections between neurons)

Classic tobacco pipe

2 California and Los Angeles County have been national leaders in instituting effective tobacco control policies and programs, resulting in even lower rates of smoking statewide (12% in 2016) and in the county (13% in 2015)

It would suggest that his character is returning to help an old friend, rather than introducing him back to the main series and implying that he is needed for the new MCRT to function