Characteristics and mechanism of initial continuous current (ICC) pulses and M components in rocket-triggered lightning were investigated in detailed. The geometric mean current peak, risetime from 10% to 90% peak, half-peak width, and charge transfer of M components were 400 A, 207 $\umu$ s, 267 $\umu$ s, and 0.19 C, respectively, exhibiting more pronounced impulsive feature than ICC pulses of which the counterpart parameters were 190 A, 462 $\umu$ s, 845 $\umu$ s, and 0.27 C, respectively. A shorter time interval between the prior return stroke (RS) and the following M component (T $_RS-M$ ) facilitated a stronger M component having larger peak while shorter pulsewidth. In two cases with extremely long lasting ICC and continuing current (CC), 20 Initial continuous current pulses occurred during a 715.3-ms duration and 15 M components occurred during a 218-ms duration. The multiple occurrences of current surges serve to keep the grounding channel active and extend the channel network inside the cloud, and hence prolong the ICC/CC duration. This situation reduced the possibility of RSs thereafter. In addition to the two traditional types of in-cloud discharges that result in M component, we recognized a new scenario that involves a short-term interruption of the upward RS wave and a reactivated breakdown promoted by the residual charge inside the main channel.